WO1995015009A1 - Porous crystalline materials having nonlinear optical properties - Google Patents

Abstract

A material exhibiting third order nonlinear optic properties includes quantum size clusters of semiconducting guest material incoroporated into the pores of M41S material in an arrangement to provide nonlinear optic properties. A material exhibiting second order nonlinear optic properties includes an organic guest material incorporated into the pores of M41S material so that a non-centrosymmetric structure is formed which will provide second harmonic generation when subjected to electromagnetic radiation of a selected frequency.

Description

POROUS CRYSTALLINE MATERIALS HAVING NONLINEAR OPTICAL PROPERTIES

This invention relates to porous crystalline materials having nonlinear optical properties.

Porous inorganic solids have found great utility as catalysts and separation media for industrial application. The openness of their icrostructure allows molecules access to the relatively large surface areas of these materials that enhance their catalytic and sorptive activity. The porous materials in use today can be sorted into three broad categories using the details of their microstructure as a basis for classification. These categories are the amorphous and paracrystalline materials, the crystalline molecular sieves and modified layered materials. The detailed differences in the microstructures of these materials manifest themselves as important differences in the catalytic and sorptive behavior of the materials, as well as in differences in various observable properties used to characterize them, such as their surface area, the sizes of their pores and the variability in those sizes, the presence or absence of X-ray diffraction patterns and the details in such patterns, and the appearance of the materials when their microstructure is studied by transmission electron microscopy and electron diffraction.

Amorphous and paracrystalline materials represent an important class of porous inorganic solids that have been used for many years in industrial applications. Typical examples of these materials are the amorphous silicas commonly used in catalyst formulations and the paracrystalline transitional aluminas used as solid acid catalysts and petroleum reforming catalyst supports.

The term "amorphous" is used herein to indicate a material with no long range order so that the pores of the material tend to be distributed over a wide range of sizes. An alternate term that has been used to describe these materials is "X-ray indifferent", since the lack of order also manifests itself in the X-ray diffraction pattern, which is usually featureless. The porosity of amorphous materials, such as the amorphous silicas, generally results from voids between the individual particles. Paracrystalline materials such as the transitional aluminas also have a wide distribution of pore size, but better defined X-ray diffraction patterns usually consisting of a few broad peaks. The microstructure of these materials consists of tiny crystalline regions of condensed alumina phases and the porosity of the materials results from irregular voids between these regions (K. efers and Chanakya Misra, "Oxides and Hydroxides of Aluminum", Technical Paper No. 19 Revised, Alcoa Research Laboratories, p. 54-59, 1987). The size of the pores in amorphous and paracrystalline materials fall into a regime called the esoporous range which, for the purposes of this application, is from 1.3 to 20 nm.

In sharp contrast to these structurally ill-defined solids are materials whose pore size distribution is very narrow because it is controlled by the precisely repeating crystalline units of the three-dimensional framework of the material. These materials are called "molecular sieves", the most important examples of which are zeolites. The precise crystalline microstructure of most zeolites manifests itself in a well-defined X-ray diffraction pattern that usually contains many sharp maxima and that serves to uniquely define the material. Similarly, the dimensions of pores in these materials are very regular, due to the precise repetition of the crystalline microstructure. All molecular sieves discovered to date have pore sizes in the microporous range, which is usually quoted as 0.2 to 2 nm, with the largest reported being about 1.2 nm. In layered materials, the interatomic bonding in two directions of the crystalline lattice is substantially different from that in the third direction, resulting in a structure that contains cohesive units resembling sheets. Usually, the bonding between the atoms within these sheets is highly covalent, while adjacent layers are held together by ionic forces or van der Waals interactions. These latter forces can frequently be neutralised by relatively modest chemical means, while the bonding between atoms within the layers remains intact and unaffected.

Thus in certain layered materials, adjacent layers may be urged apart with a swelling agent and then fixed in this separated position by the insertion of pillars to provide a material having a large degree of porosity. For example, certain clays may be swollen with water, whereby the layers of the clay are spaced apart by water molecules. Other layered materials are not swellable with water, but may be swollen with certain organic swelling agents εuch as amines and quaternary ammonium compounds. Examples of such non- water swellable layered materials are described in U.S. Patent 4,859,648 and include layered silicates, magadiite, kenyaite, trititanates and perovskites. Another example of a non-water swellable layered material, which can be swollen with certain organic swelling agents, is a vacancy- containing titanometallate material, as described in U.S. Patent 4,831,006. The X-ray diffraction patterns of pillared layered materials can vary considerably, depending on the degree that swelling and pillaring disrupt the otherwise usually well-ordered layered microstructure. The regularity of the microstructure in some pillared layered materials is so badly disrupted that only one peak_in the low angle region on the X-ray diffraction pattern is observed, at a d- spacing corresponding to the interlayer repeat in the pillared material. Less disrupted materials may show several peaks in this region that are generally orders of this fundamental repeat. X-ray reflections from the crystalline structure of the layers are also sometimes observed. The pore size distribution in these pillared layered materials is narrower than those in amorphous and paracrystalline materials but broader than that in crystalline framework materials. Layered materials frequently adopt sheetlike morphology mirroring the disparity in bonding that exists on the atomic level. Such morphological properties can be revealed by transmission electron microscopy.

A series of inorganic, non-layered esoporous crystalline materials have been recently developed which have an arrangement of uniformly-sized pores with a maximum perpendicular cross-section pore dimension of at least 13 Angstroms, and within the range of 13 to 200 Angstroms. U.S. Patent Nos. 5,098,684, 5,102,643 and 5,145,816 describe these mesoporous crystalline materials, referred

-to herein as M41S materials, and a number of techniques for synthesizing such materials.

As discussed generally by Ozin et al. in Angew. Chem. Int. Ed. En l. 28 (1988) 359-376, various potential applications for zeolites have been recognized. These include hydrocarbon conversion, gas separation, zeolite electrodes and electron relays, intrazeolite semiconductors, and optozeolite chemical sensors, just to name a few. Semiconductor materials, such as CdS, CdSe and PbS, all of which are relatively narrow band width semiconductors, have been incorporated within zeolites. Quantum structures may accordingly be obtained wherein the physical properties (e.g. electrical, optical and magnetic) differ from those of the same materials in bulk form. Quantum effects have long been known in semiconductor heterostructures prepared by molecular-beam epitaxy.

The properties of molecular sieves loaded with various materials are dependent upon a number of factors. The physical structures of the sieve and the guest material are two such factors. Others include interactions between the host and guest materials as well as guest-guest interactions.

Most molecular sieves have relatively small pore sizes. As there is no way of tailoring the pore sizes of such sieves, there is nothing one can do but use a different sieve if the pore size of the first chosen sieve is inappropriate. Using a different sieve, however, changes many variables other than pore size, some of which may be unpredictable. Thermal stability of a host material is usually preferable. Most known large pore molecular sieve materials are thermally unstable. Materials such as glass are thermally stable, but are amorphous.

According to the invention, it has now been realised that the newly produced M41S materials offer thermal stability and uniformity in pore size. The average pore size thereof may be tailored during the manufacturing process for a particular use.

Non Linear Optics Nonlinear optical (NLO) components find applications in diverse areas of optoelectronics including optical communication, laser scanning and control functions, and integrated optics technology.

The field of nonlinear optics is concerned with introduction of electric fields in a medium in such a way as to produce a new field altered in phase, amplitude, frequency, or other propagation characteristics. Adjunct characteristics of the medium such as ease of preparation, compatibility with microelectric processing methods, adhesion, mechanical and other properties are often the factors which determine the technological utility of nonlinear optical materials. Adjunct properties remain the main obstacle to application and constitute the major challenge for chemical research. Categories of application for nonlinear optical materials find specific applications in devices such as frequency doublers, frequency mixers and parametric amplifiers.

Media exhibiting NLO effects are known to consist in certain cases of porous crystalline aluminosilicate or aluminophosphate molecular sieves loaded with organic guest molecules packed in a polar arrangement. In these cases the zeolite species must display ideal pore dimensions for the alignment of these aromatic sorbates. As described by Cox, S.D. et al., "Second Harmonic Generation by the Self- Aggregation of Organic Guests in Molecular Sieve Hosts", J. Am. Chem. Soc. 110 (1988) 2986, a nonlinear optical material has been provided by loading the pores of a molecular sieve with an organic guest. Specifically, p- nitroaniline was loaded into an acentric zeolite, ALPO-5. The resulting structure showed maximum second harmonic generation (SHG) at full loading. In contrast, the same organic guest loaded in Zeolites Omega and Mordenite showed no SHG. These zeolites are centrosymmetric. 2-methyl-p- nitroaniline, which show SHG by itself, was found to lose this property when loaded in ALPO-5. It is apparent that various host-gest interactions are important with respect to NLO properties which may be obtained through the use of molecular sieves.

The polarization (coulomb/meter²) produced in a medium by a local field may be expressed in terms of a Taylor series expansion:

P_i=α_ijE(ω)+β_ijkE_j(ω)E_k(ω)+γi_jklE_j(ω)E_k(ω)E₁(ω)+-.. where 0.^,5^, and γ_i;jkl, are, respectively the components of a second order, third order, and fourth order tensor. The nonlinear terms give rise to nonlinear effects. Tensor components above second order characterize the nonlinear response of the medium to the applied local field.

Second-Order Nonlinearity The two main second-order NLO effects which are exploited in electronic devices are linear electro-optic (LEO) modulation and second harmonic generation (SHG) . When an NLO-crystal is illuminated by electromagnetic radiation of frequencies ω. and ω₂, then the result of the 3_ijk term in the local field expansion or of χ⁽²⁾ _ijk in the applied field expansion is the generation of an electromagnetic field frequency (ω, + ω₂₎ and ω. - ω₂) .

When the two fields have the same frequency (ω^ ω₂) (are degenerate) , the sum frequency is generated at 2ω or double the fundamental frequency. A well known freqency-doubler of infrared radiation from the Nd:YAG(λ=l.06 μm) to a green line(λ/2=0.053 μm or 532 nm) in the optical spectrum is KTP (KTiOPO .

Passage of light through a second-order nonlinear optical material must also produce a static (DC) (in addition to the second harmonic) field (potential) across the material — a phenomenon termed "optical rectification." All NLO materials will be characterized by a third rank tensor property called the electro-optical coefficient tensor. The components of this tensor are related to the second-order susceptibility, χ^{( )} _ijk. In LEO modulation a light beam is passed through a material subjected to an electric field via attached electrodes. The applied field causes shifts in polarization and/or phase which can be converted into amplitude changes by interference with the main beam (Mach-Zehnder interferometer) or by means of a polarization device.

Third-Order Nonlinearity Third-order nonlinear optical effects include the Kerr effect, optical bistability, optical phase conjugation, photorefractivity, and third harmonic generation (THG) . Applications of these effects include optical switching, amplification, beam steering and clean-up, and image processing. There are no symmetry constraints relating to the appearance of third-order susceptibility. Both single crystals and powders have potential utility. Large single crystals are not required. Within certain limits, fabricability may be as important as the magnitude of the effect. The effects are of two kinds: (1) those that influence the local index of refraction (n₂ effects) , (2) those that influence the absorption (resonant or photochromatic effects) . In all of these, the behavior of one light beam is influenced in some way by the presence of another.

In one aspect, the present invention is directed to a composition exhibiting third order nonlinear optical properties, comprising: a host material comprising an inorganic, porous, non-layered crystalline phase material exhibiting, after calcination, an arrangement of uniformly sized pores adapted in size, shape and chemical stereospecificity to fix an inorganic, semiconducting guest material therein in an arrangement to provide nonlinear optical properties, said pores having diameters of at least 13 Angstrom units, said phase material exhibiting an X-ray diffraction pattern with at least one peak at a position greater than 18 Angstrom units d-spacing and exhibiting a benzene adsorption capacity of greater than 15 grams benzene per 100 grams of said phase material at 6.7 kPa (50 torr) and 25°C, and quantum size clusters of said guest material incorporated into the pores of said host material. In a further aspect, the invention is directed to a composition exhibiting second order nonlinear optical properties, comprising: a host material comprising an inorganic, porous, non-layered crystalline phase material exhibiting, after calcination, an arrangement of uniformly sized pores, said pores having diameters of at least 13 Angstrom units, said host material exhibiting an X-ray diffraction pattern with at least one peak at a position greater than 18 Angstrom units d-spacing and exhibiting a benzene adsorption capacity of greater than 15 grams benzene per 100 grams of said phase material at 6.7 kPa (50 torr) and 25°C, and an organic guest material incorporated into the pores of said host material, said organic guest material displaying non-centrosymmetry and the composition providing second harmonic generation when subjected to electromagnetic radiation of a selected frequency. The host material is preferably a high-silica structure containing essentially no aluminum.

The host material preferably has a hexagonal arrangement of uniformly-sized pores at least 13 Angstrom Units in diameter and exhibits, after calcination, a hexagonal diffraction pattern that can be indexed with a d₁₀₀ value greater than 18 Angstrom Units. The pore size of the host material is selected to provide together with the guest material, the properties which are considered most desirable in the resulting host-guest system. It may be desirable in some instances for the host to exert a large influence on the confined guest. In such cases, the pore diameter should not greatly exceed the diameter of the guest particles. Semiconductor materials having relatively large band gaps, such as copper halides, are among the guest materials which require confinement in order to more readily transfer electrons. Larger pores may be employed where the band gap is relatively small. Semiconductor materials such as germanium and gallium arsenide have relatively small band gaps. When incorporated as clusters within the host material, the clusters themselves will tend to confine the electrons. The host material accordingly is not required to provide this function. Although it is not required to confine the electrons of certain semiconductor materials having narrow band gaps, it may nevertheless be desirable to select relatively small pore diameters for other reasons, such as limiting cluster or crystal size. The production of substantially homogeneous semiconductor superlattices from the interconnection of quantum "dots" iε preferably accomplished through the use of relatively small pore diameters of the host material. It will be appreciated that the term "relatively small" as used in connection with the host material described above is actually quite large in comparison to conventional molecular sieves having thermal stability. THIRD ORDER NONLINEARITY

For third order non-linear optical effects guest materials may be single elemental such as C, Ge or Si, binary, or ternary such as LiNb0₂.

Binary compoundε can consist of one element in combination with a second element of another column in the periodic table such aε III-V, II-VI and IV-VI.

Accordingly, the III-V family includes, for example, AlSb,

BN, BP, GaN, GaSb, GaAs, GaP, InSb, InAs, InP. The II-VI family includes, for example, ZnS and CdS which are often used in photoconductive devices; also CdSi, CdTe and ZnO.

The IV-VI family includes, for example, PbS, PbSe and PbTe which are sensitive in photoconductivity.

In constructing confined quantum dots for NLO application, it is desirable that the crystal size be controlled and that the crystallites bear some special ordering with respect to each other. By utilizing M41S materials, such arrangement are possible. Surface hydroxyl groups of M41S can anchor one atomic component of a semiconducting material and the second component introduced via gas or liquid phase for reaction with the first component. Loading with gallium arsenide or lead iodide will be used as non-limiting examples.

The decomposition of Lewis acid base couples of III-V materials at M41S internal silanol sites can utilize group III metal-organic compounds and group V hydrogen compounds as follows:

Si-OH + Ga(CH₃)₃ >• Si-0-Ga(CH₃)₂ + CH₄.

The Si-0-Ga(CH₃)₂ is then reacted with

AsR₃/additional reductant (R = H,X, alkane, etc.) at high temperature to produce the desired GaAs material. This type of reaction results in the formation of isolated depoεited particles of GaAs at available M41S silanol εites. Theεe particleε agglomerate to form larger crystalε when heated at, e.g. 400°C-750°C. The temperature uεed dependε on the metals uεed and can be determined with routine experimentation.

A commonly used process for the epitaxial growth of binary compounds such as III-V is chemical vapor deposition. For example, GaAs may be prepared by the reaction of trimethylgallium ((CH₃)₃Ga) and AsH₃, trimethyl or tertiary butyl arsine in hydrogen at 550°C to 750"C.

The reaction ultimately leads to the production of GaAs via methane elimination.

Traditional gas phase decomposition of the GaAs from volatile precursors can be initiated by sorption/decomposition. For example, (CH₃)₃Ga and (CH₃)₃As can be sorbed into the pore system thus forming the adduct (CH₃)₃Ga:As(CH₃)₃ within the pore. Subsequent thermal treatment results in the losε of the alkane and formation of GaAs within the pore. The crystal size and morphology is constrained by the pore dimensions.

In another embodiment a halogen transport reaction may be uεed aε followε: 2 GaCl₃ + ( (CH₃)₃Si)₃Aε AsCl₃Ga₂ +

3(CH₃)₃SiCl which upon heating forms GaAs as follows: AsCl₃Ga₂ ^ GaAs + GaCl₃.

This method allows more strandε of GaAs to be generated per cm² of external surface area by uεing M41S of smaller pore εize, e.g., 20 Angstroms.

M41S can also be loaded with AεCl₃Ga₂ using a solvent method. GaCl₃ is diεsolved in a solvent which iε preferably non-aqueous and the solution iε adεorbed into the poreε of M41S. The solvent iε removed and ( (CH₃)₃Si)₃As is introduced by abεorption into the remaining pore volume from a solvent in which GaCl₃ is not soluble. AsCl₃Ga₂ is formed within the pores and upon heating, GaAε is formed as described above. Compounds such as GaAs may be grown as single crystals. For this purpose, the guest loaded M41S is heat- treated in an electric field in order to orient the crystallites to enable them to join and form larger crystalε the size of which is limited only by the εize of the pore and the III-V compound available within the poreε. Single cryεtals -formed in this manner may be liberated by dissolving the M41S materials. The liberated crystalε can again be oriented in an electric field. This orientation can be carried out in a dilute solution of a resin, so that the crystals can be fixed in this parallel poεition by the resin after evaporation of the εolvent.

Colloidal solutions of binary compounds may be prepared in solvents such as pyridine or quinoline. Colloidal particles, e.g., 30 Angstrom particles of GaAs, can be allowed to aggregate to strands in the pores of M41S materials of a pore diameter greater than 30 Angstroms, e.g., 40 Angstroms. The M41S preferably contains eεsentially no aluminum. The strand aggregation forms so that one εide of the M41S particle haε the Ga expoεed, while the other εide has As. Colloidal solutions of Pt, Pd, Au and other metals can also be accommodated within the unusually large poreε of M41S.

In another embodiment, crystals of lead iodide (Pbl₂) can be grown in the interior of the M41S channel by melt/vapor deposition techniques, or by ion exchange of Pb³⁺ followed by treatment with iodine.

Some semiconductors are characterized by layered structureε. The interaction within a layer iε significantly stronger than that between layers.

Semiconductors of this type include Pbl₂, GaSe and various transition metal dichalcogenideε εuch aε SnSe₂ and MoS₂. Layerε can result from repetitions of the loading step. A layering effect also occurs within some semiconducting materials such as in molybdenum sulfide.

Narrow band gap species like CdS, CdSe and PbS can be introduced by ion exchange of the metal, e.g., using a nitrate solution of Cd or Pb followed by expoεure to H₂S or H₂Se under thermal conditions.

SECOND ORDER NONLINEARITY Organometallic compounds may be used as the quest material for second harmonic generation (SHG) . Inclusion guests for second harmonic generation are organic conjugated π-election moleculeε with attached electron donor and electron attracting groupε and with a noncentrosymmetric configuration when incorporated into the M41S mesoporous crystalline material. These inclusion guests are organic molecules and may be called εorbates or chromophores.

Known inclusion guests of this type include p- nitroaniline (NA) , N,N-dimethyl-p-nitroaniline (DMNA) , N- methyl-p-nitroaniline (NMNA) , 2-methyl-4-nitroaniline (MNA) , meta-nitroaniline (mNA) , 2-amino-4-nitropyridine (ANP) , 2- amino-4-nitropyrimidine (ANPm) , 4-nitropyridine N-oxide (NPNO) , 4-N,N'-(dimethylamino) -4 ' nitrostilbene (DANS), benzene chromium tricarbonyl (benzene Cr(C0₃)), cyclohexadiene iron tricarbonyl (cyclohexadiene Fe(CO)₃), cyclopentadienylmanganese tricarbonyl (cyclopentadienyl Mn(CO)₃), p-amino-p'-nitrobiphenyl, p-amino-p'- nitrodiphenyl, p-amino-p'-nitrodiphenyldiacetylene, p-(methylthio) -p'-nitrophenyldiacetylene, and other diacetylenes.

Other nonlinear optically active organic compounds are 13, 13-diamino-14, 14-dicyanodiphenoquinodimethane, and similar - quinodimethanes such as tetracyano quinodimethane (TCNQ) salts.

The organometallic compounds possesε large second order polarizabilities and pi conjugated systems.

For guest-host inclusion complexation of organometallic sorbates into M41S, an organic compound such as thiourea is dissolved in a solvent such as methanol and the solution is sorbed into M41S substrate structure. Then the organometallic compound such as benzene chromium tricarcarboxyl (C₆H₅Cr(CO)₃) is dissolved in a solvent in which it is soluble and this solution introduced into the M41S. After the solvent is evaporated, the inclusion compound thiourea-C₆H₅Cr(C0₃) will form. Because this material has been crystallized within the pore of the M41S substrate, the incluεion compound will arrange in a specific order because of the εpecific geometry of the pore. Aε where inorganic materialε are incorporated within the hoεt material, the pore εize and εtructure will at leaεt partially influence the properties of the guest-hoεt system. If the host material iε to contribute εignificantly to the orientation of the guest, the pore εize thereof should be relatively small so that the walls -defining each pore can exert maximum influence upon the guest. Alternatively, if the primary function of the host material is εimply to provide support for or enhance the thermal stability of an organic guest, the pores should be relatively large in comparison to the guest molecules or crystals. The guest-host system provided by this embodiment of the invention preferably exhibits SHG properties.

MESOPOROUS CRYSTALLINE MATERIAL The crystalline (i.e. meant here as having sufficient order to provide, after calcination, a diffraction pattern with at least one peak by, for example, X-ray, electron or neutron diffraction) host material of this invention may be characterized by its heretofore unknown structure, including extremely large pore windows, and high sorption capacity. In general, the material of the invention iε "meεoporous", by which is meant that the material has uniform pores of diameter within the range of 1.3 to 20 nm. More preferably, the materials of the invention have uniform pores of diameter within the range 1.8 to 10 nm. In this respect, pore size is considered as the maximum perpendicular cross-sectional dimension of the pore.

The host material of the preεent invention can be diεtinguiεhed from other porous inorganic εolids by the regularity of its large open pores, whose size more nearly resembles that of amorphous or paracryεtalline materialε, but whoεe regular arrangement and uniformity of εize (pore size distribution within a single phase of, for example, + 25%, uεually + 15% or leεs of the average pore size of that phase) more closely resemble thoεe of crystalline framework materials such as zeolites.

In the preferred arrangement, the porosity of the crystalline host material of the invention is provided by a generally hexagonal arrangement of open channelε, a property that can be readily observed by electron

-diffraction and transmission electron microscopy. In particular, the tranεmisεion electron micrograph of properly oriented specimens of the material show a hexagonal arrangement of large channels and the corresponding electron diffraction pattern gives an approximately hexagonal arrangement of diffraction maxima. The d₁₀₀ spacing of the electron diffraction patterns is the distance between adjacent spots on the hkO projection of the hexagonal lattice and is related to the repeat distance a₀ between channels obεerved in the electron micrographε through the formula d₁₀₀ = a₀ 73/2. Thiε d₁₀₀ εpacing observed in the electron diffraction patterns corresponds to the d-spacing of a low angle peak in the X-ray diffraction pattern of the material. The most highly ordered preparations of the material obtained so far have

20-40 distinct spots observable in the electron diffraction patterns. These patternε can be indexed with the hexagonal hkO εubεet of unique reflectionε of 100, 110, 200, 210, etc., and their εymmetry-related reflections. In thiε reεpect, it iε to be understood that the reference to a hexagonal arrangement of channels is intended to encompaεs not only mathematically perfect hexagonal symmetry but also an an arrangement in which most channels in the material are surrounded by six nearest neighbor channelε at substantially the same diεtance. Defectε and imperfectionε will cauεe εignificant numberε of channels to violate this criterion to varying degrees. Sampleε which exhibit aε much aε + 25% random deviation from the average repeat diεtance between adjacent channels still clearly give recognizable images of the present ultra-large pore materials.

The most regular preparations of the preferred host material of the invention give a hexagonal X-ray diffraction pattern with a few distinct maxima in the extreme low angle region. The X-ray diffraction pattern, however, iε not alwayε a sufficient indicator of the presence of these materials, as the degree of regularity in the microstructure and the extent of repetition of the structure within individual particles affect the number of peaks that will be observed. Indeed, preparations with only one distinct peak in the low angle region of the X-ray diffraction pattern have been found to contain subεtantial amountε of the material of the invention.

In itε calcined form, the crystalline host material of the invention may be further characterized by an X-ray diffraction pattern with at least one peak at a position greater than about 1.8 nm d-spacing (4.909 degrees two- theta for Cu K-alpha radiation) which correspondε to the d₁₀₀ value of the electron diffraction pattern of the material. More preferably, the calcined cryεtalline hoεt material of the invention is characterized by an X-ray diffraction pattern with at least two peaks at poεitionε greater than about 1 nm d-spacing (8.842 degrees two-theta for Cu K-alpha radiation) , at least one of which is at a position greater than 1.8 nm d-spacing, and no peaks at positionε less than 1 nm d-spacing with relative intensity greater than about 20% of the strongest peak. Still more particularly, the X-ray diffraction pattern of the calcined material of this invention has no peaks at positions less than 1 nm d-spacing with relative intensity greater than about 10% of the strongeεt peak. In the preferred hexagonal arrangement, at least one peak in the X-ray pattern will have a d-spacing correεponding to the d₁₀₀ value of the electron diffraction pattern of the material. X-ray diffraction data referred to herein were collected on a Scintag PAD X automated diffraction system employing theta-theta geometry, Cu K-alpha radiation, and an energy dispersive X-ray detector. Uεe of the energy diεpersive X-ray detector eliminated the need for incident or diffracted beam monochromators. Both the incident and diffracted X-ray beams were collimated by double slit incident and diffracted collimation systems. The slit sizes used, starting from the X-ray tube source, were 0.5, 1.0, 0.3 and 0.2 mm, reεpectively. Different εlit systems may produce differing intensities for the peaks. The materials of the present invention that have the largeεt pore sizes may require more highly collimated incident X- ray beams in order to reεolve the low angle peak from the transmitted incident X-ray beam.

The diffraction data were recorded by step-scanning at 0.04 degrees of two-theta, where theta is the Bragg angle, and a counting time of 10 seconds for each step. The interplanar εpacings, d's, were calculated in nanometers (nm) , and the relative intensities of the lines, I/I₀, where I₀ iε one-hundredth of the intenεity of the εtrongest line, above background, were derived with the use of a profile fitting routine. The intenεities were uncorrected for Lorentz and polarization effects. The relative intensities are given in terms of the symbols vs = very strong (75-100) , s = strong (50-74) , m = medium (25-49) and w = weak (0-24) . It should be understood that diffraction data listed as single lines may consist of multiple overlapping lines which under certain conditions, such as very high experimental resolution or cryεtallographic changes, may appear as resolved or partially resolved lineε. Typically, crystallographic changes can include minor changeε in unit cell parameterε and/or a change in crystal symmetry, without a substantial change in structure. These minor effects, including changes in relative intenεities, can also occur as a result of differences in cation content, framework composition, nature and degree of pore filling, thermal and/or hydrothermal history, and peak width/shape variations due to particle size/shape effects, structural diεorder or other factorε known to those skilled in the art of X-ray diffraction. The host material of the invention exhibits an equilibrium benzene adεorption capacity of greater than about 15 gramε benzene/100 gramε cryεtal at 6.7 kPa (50 torr) and 25°C. The equilibrium benzene adεorption capacity must, of course, be measured on a sample which exhibitε no pore blockage by incidental contaminantε. For example, water should be removed by dehydration techniques, e.g. thermal treatment, whereas inorganic amorphouε materialε, e.g. silica, and organicε should be removed by contact with acid or base or other chemical agents and/or physical methods (such as, calcination) so that the detrital material is removed without detrimental effect on the material of the invention.

In general, crystalline host material of this invention^{^}has the following compoεition: M_n/q^(Wa ^xb ^Yc ^Zd V wherein W iε a divalent element, εuch aε a divalent firεt row tranεition metal, e.g. manganese, cobalt, nickel, iron, and/or magnesium, preferably cobalt; X is a trivalent element, such as aluminum, boron, chromium iron and/or gallium, preferably aluminum; Y is a tetravalent element such as silicon and/or germanium, preferably εilicon; Z iε a pentavalent element, such as phosphorus; M is one or more ions, such aε, for example, ammonium, Group IA, IIA and VIIB ions, uεually hydrogen, sodium and/or fluoride ions; n is the charge of the composition excluding M expreεεed as oxideε; q iε the weighted molar average valence of M; n/q iε the number of moleε or mole fraction of M; a, b, c, and d are mole fractionε of W, X, Y and Z, respectively; h is a number of from 1 to 2.5; and (a+b+c+d) = 1.

A preferred embodiment of the above crystalline material is when (a-t-b+c) is greater than d, and h = 2. More preferably, when h = 2, a = 0 and d = 0.

In the as-synthesized form, the host material of this invention has a composition, on an anhydrous basiε, expreεsed empirically as follows: rRM„_/q(W_a X_b Y_c Z_d 0_h) wherein R is the total organic material used to assist in the synthesis of the material and not included in M as an ion, and r is the coefficient for R, i.e. the number of moleε or mole fraction of R. The M and R componentε are asεociated with the material aε a reεult of their preεence during cryεtallization, and are easily removed or, in the case of M, replaced by post- crystallization methods hereinafter more particularly described. For example, the original M, e.g. sodium or chloride, ions of the as-synthesized material of this invention can be replaced by ion exchange with other ions. Preferred replacing ions include metal ions, hydrogen ions, hydrogen precursor, e.g. ammonium, ions and mixtures thereof. Host materials having the composition defined by the above formula can be prepared from a reaction mixture having a compoεition in termε of mole ratioε of oxideε, within the following rangeε: Reactantε Uεeful Preferred

X₂0₃/Y0₂ 0 to 0 . 5 0.001 to 0.5

X₂0₃/ (Y0₂+Z₂0₅ ) 0 . 1 to 100 0 . 1 to 20

X₂0₃/ (Y0₂+WO+Z₂0₅ ) 0 . 1 to 100 0.1 to 20 Solvent/ (Y0₂+WO+Z₂0₅+X₂0₃ ) 1 to 1500 5 to 1000

OH^_/Y0₂ 0 to 10 0 to 5 (M_2/eO+R_2/fO) /

(Y0₂+WO+Z₂0₅+X₂0₃ ) 0. 01 to 20 0.05 to 5

M_2/βO/ (Y0₂+WO+Z₂0₅+X₂0₃ ) 0 to 10 0 to 5 -

R_2/fO/ (Y0₂+WO+Z₂0₅+X₂0₃ ) 0 . 01 to 2 . 0 0.03 to 1.0

wherein e and f are the weighted average valences of M and R, reεpectively, wherein the solvent is a C_α to C₆ alcohol or diol, or, more preferably, water and wherein R compriseε an organic directing agent having the formula R₁R₂R₃R₄Q⁺ wherein Q iε nitrogen or phosphoruε and wherein at leaεt one of R- , R₂, R₃ and R₄ is aryl or alkyl group having 6 to 36 carbon atoms, e.g. -C₆H₁₃, -C₁₀H₂₁ , -C₁₆H₃₃ and -C₁₈H₃₇, and each of the remainder of R_{l f} R₂, R₃ and R₄ iε selected from hydrogen and an alkyl group having 1 to 5 carbon atoms. The compound from which the above ammonium or phosphonium ion is derived may be, for example, the hydroxide, halide, silicate or mixtures thereof.

The particular effectiveness of the above directing agent, when compared with other such agents known to direct synthesis of one or more other crystal structureε, iε believed due to itε ability to function aε a template in the nucleation and growth of the desired ultra-large pore materials. Non-limiting examples of these directing agents include cetyltrimethylammonium, cetyltrimethylphosphonium, octadecyltrimeth lphosphonium, benzyltrimethylammonium, cetylpyridinium, myristyltrimethylammonium, decyltrimethylammonium, dodecyltrimethylammonium and dimethyldidodecylammonium compounds.

Preferably, the total organic, R, present in the reaction mixture comprises an additional organic directing agent in the form of an ammonium or phosphonium ion of the above directing agent formula but wherein each R- , R₂, R₃ and R₄ iε εelected from hydrogen and an alkyl group of 1 to 5 carbon atoms (2 of the alkyl groupε can be interconnected to form a cyclic compound) . Examples of the additional organic directing agent include tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium and pyrrolidinium compounds. The molar ratio of the first-mentioned organic directing agent to the additional organic directing agent can be in the range 100/1 to 0.01/1. Where the additional organic directing agent is present, the molar ratio R_2/fO/(Y0₂+WO+Z₂0₅+X₂0₃) in the reaction mixture is preferably 0.1 to 2.0, most preferably 0.12 to 1.0. In addition, to vary the pore size of the final crystalline phase material, the total organic, R, in the reaction mixture can include an auxiliary organic in addition to the organic directing agent(s) described above. This auxiliary organic is εelected from (1) aromatic hydrocarbons and amines having 5-20 carbon atoms and halogen- and C₁-C₁₄ alkyl-substituted derivatives thereof, (2) cyclic and polycyclic aliphatic hydrocarbons and amines of 5 to 20 carbon atoms and halogen- and C₁-C₁₄ alkyl-substituted derivatives thereof and (3) straight and branched chain aliphatic hydrocarbons and amines having 3-16 carbon atoms and halogen-substituted derivatives thereof.

In the above auxiliary organics, the halogen εubstituent is preferably bromine. The Cj-C₁₄ alkyl substituent may be a linear or branched aliphatic chain, εuch as, for example, methyl, ethyl, propyl, isopropyl, butyl, pentyl and combinations thereof. Examples of these auxiliary organics include, for example, p-xylene, trimethylbenzene, triethylbenzene and triiεopropylbenzene.

With the inclusion of the auxiliary organic in the reaction- mixture, the mole ratio of auxiliary organic/Y0₂ will be from 0.05 to 20, preferably from 0.1 to 10, and the mole ratio of auxiliary organic/organic directing agent(s) will be from 0.02 to 100, preferably from 0.05 to 35.

When a source of silicon iε uεed in the εyntheεiε method, it is preferred to use at least in part an organic silicate, such as, for example, a quaternary ammonium silicate. Non-limiting examples of such a silicate include tetramethylammonium silicate and tetraethylorthosilicate.

Non-limiting examples of variouε combinations of W, X, Y and Z contemplated for the above reaction mixture include: w X y

— Al Si

— Al — P

— Al Si P C CoO A All — — P

Co Al Si P

— — Si

including the combinations of W being Mg, or an element selected from the divalent first row transition metals, e.g. Mn, Co and Fe; X being B, Ga or Fe; and Y being Ge.

To produce the crystalline host material of the invention, the reaction mixture described above is maintained at a temperature of 25 to 250°C, preferably 50 to 175°C, and preferably a pH of 9 to 14 for a period of time until the required crystals form, typically 5 minutes to 14 days, more preferably 1 to 300 hours.

When the cryεtalline material of the invention is an aluminosilicate, the synthesis method conveniently involves the following steps:

(1) Mix the organic (R) directing agent with the solvent or εolvent mixture such that the mole ratio of solvent/R_2/fO is within the range of 50 to 800, preferably from 50 to 500. This mixture conεtitutes the "primary template" for the synthesiε method.

(2) To the primary template mixture of step (1) add the silica and alumina such that the ratio of ^R _2/f°/ (Si0₂+Al₂0₃) is within the range 0.01 to 2.0. (3) Agitate the mixture reεulting from εtep (2) at a temperature of 20 to 40°C, preferably for 5 minutes to 3 hours.

(4) Allow the mixture to stand with or without agitation, preferably at 20 to 50°C, and preferably for 10 minutes to 24 hourε.

(5) Crystallize the product from step (4) at a temperature of 50 to 150"C, preferably for 1 to 72 hours.

When used as a host material, the composition of the invention should be subjected to treatment to remove part or all of any organic conεtituent. Typically, this involves thermal treatment (calcination) at a temperature of 400 to 750°C for at leaεt 1 minute and generally not longer than 20 hours, preferably from 1 to 10 hours. While subatmospheric pressure can be employed for the thermal treatment, atmospheric preεsure is desired for reasonε of convenience, εuch aε in air, nitrogen and ammonia. The invention will now be more particularly described with reference to the Examples and the accompanying drawingε in which: Figure 1 iε an X-ray diffraction pattern of the product of Example 1;

Figure 2 is an X-ray diffraction pattern of the product of Example 2; Figure 3 is an X-ray diffraction pattern of the product of Example 3.

In the examples, whenever sorption data are εet forth for compariεon of sorptive capacities for water, cyclohexane, benzene and/or n-hexane, they are equilibrium adεorption values determined as follows: A weighed sample of the adsorbent, after calcination at about 540"C for at leaεt about 1 hour and other treatment, if neceεεary, to remove any pore blocking contaminantε, iε contacted with the deεired pure adεorbate vapor in an adεorption chamber. The increaεe in weight of the adsorbent is calculated as the adsorption capacity of the sample in terms of grams/100 grams adsorbent based on adsorbent weight after calcination at about 540°C. The preεent compoεition exhibits an equilibrium benzene adεorption capacity at 50 Torr and 25"C of greater than about 15 grams/100 grams, particularly greater than about 17.5 grams/100 grams and more particularly greater than about 20 grams/100 grams. A preferred way to do this iε to contact the deεired pure adsorbate vapor in an adsorption chamber evacuated to lesε than 1 mm at conditionε of 12 Torr of water vapor, 40 Torr of n-hexane or cyclohexane vapor, or 50 Torr of benzene vapor, at 25°C. The pressure is kept constant (within about + 0.5 mm) by addition of adsorbate vapor controlled by a manostat during the adsorption period. As adsorbate is adsorbed by the new crystal, the decrease in presεure causes the manostat to open a valve which admits more adεorbate vapor to the chamber to restore the above control pressures. Sorption is complete when the pressure change is not εufficient to activate the manostat.

Another way of doing this for benzene adsorption data is on a suitable thermogravimetric analysis system, such as a computer-controlled 990/951 duPont TGA syεtem. The adεorbent εample iε dehydrated (phyεically εorbed water removed) by heating at, for example, about 350"C or 500°C to constant weight in flowing helium. If the sample is in as-syntheεized form, e.g. containing organic directing agentε, it iε calcined at about 540°C in air and held to conεtant weight inεtead of the previouεly deεcribed 350°C or 500°C treatment. Benzene adεorption iεotherms are measured at 25"C by blending a benzene saturated helium gas stream with a pure helium gaε εtream in the proper proportions to obtain the deεired benzene partial pressure. The value of the adsorption at 50 Torr of benzene is taken from a plot of adsorption isotherm. In the examples, percentageε are by weight unless otherwise indicated.

EXAMPLE 1 A. One hundred grams of a hexadecyltrimethylammonium (C₁₆Me₃N)hydroxide solution (prepared by contacting a 29 wt% N,N,N-trimethyl-l-hexadecanaminium chloride solution with a hydroxide-for-nalide exchange resin) were combined with 50.6 gramε of a tetramethylammonium silicate solution (10% Si0₂,0.5 TMA/Si0₂) , and 34 grams of cetyltrimethylammonium bromide with stirring at approximately 4°C. The pH of this mixture was adjuεted to approximately 10.0 by the addition of 51.3 grams IN H₂S0₄ solution. Thiε mixture waε placed in polypropylene bottles and put in a steambox at 100°C for 48 hours. The reεulting εolid product waε recovered by filtration and dried in air at ambient temperature. The chemical analysiε of the as-synthesized product was:

C 47.5 wt. %

Al <0.25 wt. % N 2.39 wt. %

Si 11.20 wt. %

Ash (1000°C) 24.67 wt. % The product was then calcined at 540°C for one hour in flowing nitrogen, followed by εix hourε in flowing air.

The X-ray diffraction pattern of the calcined product waε that of M41S.

B. The synthesis as in paragraph A was repeated except that the pH of the reaction mixture was adjusted to about 10 by the addition of 50.0 gramε IN H₂S0₄ solution.

The chemical analysis of the as-εynthesized product was:

C 32.6 wt. % Al <0.13 wt. %

N 1.95 wt. %

Si 7.93 wt. %

Ash (1000°C) 17.49 wt. % The product was then calcined at 540"C for one hour in flowing nitrogen followed by six hours in flowing air. The X-ray diffraction pattern of the calcined product waε that of M41S.

The Example 1 product waε prepared by compositing the preparations of 1(A) and 1(B) . X-ray diffaction pattern of the composite in shown in Figure 1 and iε that of very pure M41S.

EXAMPLE 2

A. One hundred gramε of a hexadecyltrimethylammonium

(C₁₆Me₃N)hydroxide εolution (aε described in Example 1) were combined with 50.6 grams of a tetramethylammonium silicate solution (10% Si0₂, 0.5 TMA/Si0₂) , 34 grams of cetyltrimethylammonium bromide, and 4.4 grams of a tetramethylammonium aluminate solution (prepared by dissolving 2.6 grams of aluminum wire in 150 grams of 25% tetramethylammonium hydroxide solution) with stirring at approximately 4°C. The pH of this mixture was adjusted to approximately 10.5 by the addition of 55.9 grams IN H₂S0₄ εolution. Thiε mixture waε placed in polypropylene bottles and put in a steambox at 100°C for 48 hours. The resulting εolid product waε recovered by filtration and dried in air at ambient temperature. Found in the as-synthesized product: carbon - 47.93 weight %, aluminum - 0.40 weight %, nitrogen - 3.24 weight %, silicon - 9.19 weight % and ash (1000°C) 20.74 weight %. The product was then calcined at 540°C for one hour in flowing nitrogen followed by six hourε in flowing air. The X-ray diffraction pattern of the calcined product waε that of M41S. B. The procedure of 2(A) was repeated except that the pH of the reaction mixture was adjusted to about 10.5 by the addition of 51.9 grams of IN H₂S0₄ solution. Found in as-synthesized product: carbon - 45.34 weight %, aluminum - 0.59 weight %, nitrogen - 2.92 weight %, silicon - 12.44 weight % and ash (1000°C) - 23.30 weight %. The X-ray diffraction pattern of the calcined product was that of M41S.

The Example 2 product waε prepared by compoεiting the preparationε of 2 (A) and 2 (B) . The x-ray diffraction pattern of the composite is shown in Figure 2 and is that of very pure M41S.

EXAMPLE 3 A. Two hundred and forty-three grams of a dodecyltrimethylammonium (C₁₂Me₃N)hydroxide solution (prepared by contacting a 29% dodecyltrimethylammonium bromide solution with a hydroxide-for-halide exchange resin) were combined with 30 grams of tetraethylorthosilicate, and 306 grams of a 29% (by weight) dodecyltrimethylammonium bromide εolution with stirring at approximately 4°C. This mixture was placed in polypropylene bottles and put in a steambox at 100°C for 48 hours. The resulting solid product was recovered by filtration and dried in air at ambient temperature. The product was then calcined at 540°C for one hour in flowing nitrogen, followed by εix hours in flowing air. X-ray diffraction pattern was that of M41S. Found in the as-synthesized product: carbon - 35.4 weight %, aluminum - <0.07 weight %, nitrogen - 2.56 weight %, silicon - 19.41 weight % and ash (1000"C) 41.56 weight%. B. The procedure of 3(A) waε repeated and the x-ray diffraction pattern of the calcined product waε that of M41S. Found in the aε-synthesized product: carbon - 33.7 weight %, aluminum - <0.04 weight %, nitrogen - 2.37 weight %, silicon - 20.4 weight % and ash (1000°C) 45.17 weight %. The Example 3 product was prepared by compositing the preparations of 3(A) and 3(B). The x-ray diffraction pattern of the composite is εhown in Figure 3 and is that of very pure M41S.

The products of Examples 1-3 were all suitable for use in the composition of the invention exhibiting non-linear optical properties.

EXAMPLE 4 Pbl₂ was loaded into the composite mesoporouε M41S product prepared in Example 2. Pbl₂ was loaded from a melt according to the reaction Pbl₂ (1) + Mesoporous Host (solid state mixture) = composite when heated to 425°C and held at that temperature for 20 hours, then slowly cooled. The amount of Pbl₂ waε commensurate with the pore volume, i.e. equal to or less than the pore volume. The absorption edge for the resultant product of was determined to have an onset at 535 nm and the loaded sample fluoresced at 598 nm. This is consiεtent with Pbl₂ which has a bulk absorption band with an onset at 550 nm.

EXAMPLE 5 Another synthetic approach was used. The conditions of preparation of Example 4 were applied, except that the mesoporous material was separated from the bulk Pbl₂ and vapor from the latter waε allowed to diffuse the into the bulk. The temperature of the mesophase was slightly higher than that of the bulk to prevent coating of the outside of the mesophaεe with bulk Pbl₂. The bulk temperature was 425°C and the transfer was carried out over a 20 hour period. The product was then cooled slowly .- The product was found to show an interesting spectum, with the onset of the absorption edge at 490 nm. Uεing a pump radiation of 532 nm gave the fluoreεcence for the product of Example 4 but not for the product of Example 5 εince the material abεorbs at shorter wavelengths, thus confirming the blue shift. The fluorescence of the second sample was strong and was shifted to correspondingly shorter wavelengths.

EXAMPLE 6

Gallium arsenide was deposited using a conventional metallorganic chemical vapor deposition reactor. The gallium source waε trimethylgallium (TMG) . The arεenic εource waε arsine but could be an organoarsine such as trimethyl or tertiary butylarsine. This reagent was mixed with a hydrogen carrier gas which was purified by paεsing over palladium and pasεed over the mesoporous sample which was supported on a quartz plate. While the deposition temperature can be between 550° to 750°C, in this experiment it was about 680°C. The total pressure in the reactor cell can be 101-106 kPa (760-800 torr) , and in this preparation it was 102 kPa (770 torr) at growth. The growth time was about 400 secondε for the TMG partial preεεure of 10 Pa (0.08 torr) and a partial preεεure of arεine of 67 Pa (0.5 torr). The reactor was heated inductively by a heating coil. After the reaction was completed, the εa ple waε cooled in a stream of arsine since gallium arsenide loseε arεenic at elevated temperatureε.

The fluoreεcence of the resultant product was determined to be blue shifted from the infrared (not visible) into the yellow region at about 600 nm and observable at room temperature.

Claims

CLAIMS :

1. A composition exhibiting third order nonlinear optical properties, comprising: a host material compriεing an inorganic, porouε, non-layered cryεtalline phase material exhibiting, after calcination, an arrangement of uniformly sized poreε adapted in εize, εhape and chemical stereospecificity to fix an inorganic, semiconducting guest material therein in an arrangement to provide nonlinear optical properties, said poreε having diameters of at least 13 Angstrom units, said phase material exhibiting an X-ray diffraction pattern with at leaεt one peak at a position greater than 18 Angstrom units d-spacing and exhibiting a benzene adεorption capacity of greater than 15 gramε benzene per 100 gramε of said phase material at 6.7 kPa (50 torr) and 25°C, and quantum size clusters of said guest material incorporated into the pores of said host material.

2. A composition as claimed in Claim 1 wherein said guest material iε selected from the group consiεting of Periodic Table Groupε III-V, II-VI and IV-VI semiconducting compoundε.

3. A compoεition aε claimed in Claim 2 wherein εaid gueεt material includes gallium arsenide

4. A compoεition aε claimed in Claim 1 wherein εaid gueεt material includes lead iodide.

5. A composition as claimed in any preceding Claim wherein said clusters are aggregated within said pores, thereby forming fiber-like strands of said guest material.

6. A composition aε claimed in any preceding Claim wherein the maximum average diameters of said clusters are of smaller sizeε than the diameters of said pores. 7. A composition exhibiting εecond order nonlinear optical properties, comprising: a host material compriεing an inorganic, porous, non-layered crystalline phase material exhibiting, after calcination, an arrangement of uniformly εized pores, said pores having diameters of at leaεt 13 Angεtrom unitε, said host material exhibiting an X-ray diffraction pattern with at leaεt one peak at a position greater than 18 Angstrom unitε d-εpacing and exhibiting a benzene adsorption capacity of greater than 15 grams benzene per 100 grams of said phase material at 6.

7 kPa (50 torr) and 25°C, and an organic guest material incorporated into the pores of εaid host material, said organic guest material displaying non-centrosymmetry and the compoεition providing second harmonic generation when subjected to electromagnetic radiation of a selected frequency.

8. A composition as claimed in Claim 7 wherein said guest material is selected from the group consisting of organometallic compounds, sorbates and chromophores.

9. A compoεition as claimed in any preceding Claim wherein said host material is a silicate having a hexagonal arrangement of uniformly sized pores and exhibiting, after calcination, a hexagonal electron diffraction pattern that can be indexed with a d₁₀₀ value greater than 18 Angstrom units.

10. A composition as claimed in any preceding Claim wherein crystalε of said guest material are grown within said pores.

11. A composition aε claimed in any preceding Claim wherein the host material iε a silicate containing essentially no aluminum.