Formation Of Inclusion Compounds Research Articles

Enhanced bioavailability of poorly water-soluble clotrimazole by inclusion with β-cyclodextrin

Clotrimazole, a poorly water-soluble antimycotic agent, is a promising agent for various diseases including cancer and sickle cell anemia. To improve the oral bioavailability of clotrimazole, the inclusion compound of clotrimazole with beta-cyclodextrin was prepared by spray-drying method and characterized by phase solubility, differential scanning calorimetry and dissolution. Furthermore, the pharmacokinetics after oral administration in rats was then performed compared with clotrimazole powder. The solubility of clotrimazole increased linearly as a function of beta-cyclodextrin concentration, resulting in A(L) type phase solubility diagram which revealed a formation of inclusion compound in a molar ratio of 1:2, with the apparent association constant of 230.2 M(-1). The dissolution rate of clotrimazole in the inclusion compound increased greatly compared to clotrimazole powder in pH 7.4 phosphate buffer solution. The inclusion compound gave significantly higher initial plasma concentrations, Cmax and AUC of clotrimazole than did clotrimazole powder when they were administered as suspension form, indicating that the drug from inclusion compound could be more orally absorbed in rats. Thus, the oral bioavailability of clotrimazole could be improved markedly by inclusion complexation, possibly due to an increased dissolution rate.

Formation of crystalline inclusion compounds of poly (vinyl chloride) of different stereoregularity with γ-cyclodextrin

This work reports the formation and detailed characterization of the γ-cyclodextrin (γ-CD) inclusion compounds (ICs) formed with two poly (vinyl chloride) samples with different isotactic content. The ICs were characterized by X-ray diffraction, solid state 13C-NMR, solution 1H-NMR, FT-infrared, differential scanning calorimetry, and thermogravimetric analysis. Experimental evidence of the inclusion of the guest polymer chains into the narrow channels created by the γ-CD crystalline host lattice has been obtained. Examination of coalesced poly (vinyl chlorides) (PVCs) obtained after the host γ-CD is removed reveals different characteristics specifically for the coalesced PVC sample with higher isotactic content. An increase in Tg was observed by DSC for this PVC. To the contrary, the Tg of the coalesced PVC sample with lower isotactic content is almost the same as that of the as-synthesized sample. Thermogravimetric analysis indicated that coalesced PVC with higher isotactic content acquires a degree of stabilization after modification by threading into and being extracted from its γ-CD IC. The results suggest that an irreversible conformational change takes place when PVC forms ICs with a solid host lattice like γ-CD. The PVC molecules extend and reorganize into a more stable conformation in the IC, consequently improving the properties of the coalesced sample. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2503–2513, 2007

Effect of Polyethers for Photo and Thermal Decomposition of Photosensitive Diazo Compounds

Inclusion compound formation of polyethylene glycol (PEG) with p-substituted benzene diazo compounds (SBD) in aqueous solutions was decided from activation energy (Ea) of thermal decomposition, dissociation constant Kd by Lineweaver-Burk plot modified with Michaelis-Menten formula and degradation temperature Dt, and compared with constitution of complex by WinMOPAC calculation. Thermal decomposition rate of p-chlorobenzene diazo compound (ClBD) with PEG was accelerated as with βcyclodextrine (CD) which include the benzene ring of the diazo compound. Kd of ClBD with PEG was larger than that with CD. PEG is not a ring, but a linear molecule. Dt of SBD with PEG in solid was higher than that without PEG300. Effect of molecular weight of PEG for Dt was, in a decreasing order, no additives - PEG300

Structures and photophysics of lophine and double lophine derivatives

Novel lophine (2,4,5-triphenylimidazole) derivatives, ortho-, meta- and para-substituted in the 2-phenyl ring and p-phenyl, p-tolyl, and p-anisyl rings in the 4- and 5-aryl rings and double lophine derivatives were synthesized and their physico-chemical properties were determined. We included arylimidazoles, derivatives substituted with electron-donating and electron attracting groups. MeO- and OH-groups release electrons and activate the ring. In contrast, COOH- and CN-groups withdraw electrons and deactivate the ring. Nitro derivatives of imidazole, phenol, 2-[4,5-bis(4-methoxyphenyl)-1 H-imidazole-2-yl]-4-nitro 23 and phenol, 2-[4,5-bis(4-methyl-phenyl)-1 H-imidazole-2-yl]-4-nitro 24 crystallize with guest molecules in various colors. Double imidazole derivatives of lophine, 2,2′-(2,5-thiophenediyl)bis[4,5-diphenyl-1 H-imidazole] 27 and 2,2′-(1,4-phenylene)bis[4,5-diphenyl-1 H-imidazole] 29 show piezochromism, photochromism and thermochromism in the solid state and form inclusion compounds in various colors. Four inclusion compounds in two different colors: yellow and green, depending on the solvent molecules were found for 27 and two different colors: light yellow and colorless were obtained for 29. The fluorescence intensity for 27 substituted with MeO-group in the 4,5-phenyl rings is decreased and it is increased for 29 by changing phenyl rings to MeO-substituent in the 4,5-phenyl rings. Upon irradiation with UV light at room temperature, green solution of 29 turned into orange and colorless solution of 29 turned into light yellow. The photochemical properties of 27 and 29 and their derivatives were studied by irradiating basic and neutral degassed acetonitrile solutions with medium pressure xenon lamp and their photochemical quantum yields, ranging from 0.0011 to 0.0024, together with the corresponding fluorescence quantum yields, ranging from 0.52 to 0.90 and lifetimes, ranging from 1.03 to 1.42 ns were determined. These compounds are sensitive to different external stimulations, such as UV irradiation, heat, increasing pressure, and changing of the environmental pH, causing spectral changes. Our results suggest potential applications of these compounds in molecular photonics and sensing.

Structural Studies of [CpMoL2(CO)2]+ (L = NCMe, L2 = 2,2′‐biimidazole) Complexes and Their Inclusion Compounds with Cyclodextrins

AbstractProtonation of [CpMo(η3‐C3H5)(CO)2] followed by addition of acetonitrile or 2,2′‐biimidazole (H2biim) gave the complexes [CpMo(NCMe)2(CO)2](BF4) (1) and [CpMo(H2biim)(CO)2](BF4) (2) in good yields. The structures of 1 and 2 were determined by single‐crystal X‐ray diffraction in the orthorhombic Pbca and triclinic P$\bar {1}$ space groups, respectively. Both complexes have similar metal ion coordination environments, which can be envisaged as slightly distorted pseudo‐square pyramids, a coordination geometry commonly compared with a four‐legged piano stool. The two complexes were immobilised in native and permethylated β‐cyclodextrins (β CD and TRIMEB) by methods tailored according to the stabilities and solubilities of the individual components and this gave four adducts with a 1:1 host/guest stoichiometry. The formation of true inclusion compounds was supported by powder X‐ray diffraction (XRD), thermogravimetric analysis (TGA), 13C{1H} CP/MAS NMR and FTIR spectroscopy. In the case of the TRIMEB adduct containing complex 1, the crystal packing arrangement is markedly similar to that previously reported for the corresponding 1:1 TRIMEB adducts of the neutral guests [CpMoX(CO)3] (X = Cl, CH2CONH2), featuring columns in which the macrocycles are arranged along the b axis in a tilted fashion.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Thermal degradation of polycarbonate, poly(vinyl acetate) and their blends

We have recently developed a novel approach for intimately mixing thermodynamically incompatible polymers, which utilizes the formation of inclusion compounds (ICs) formed with host cyclodextrins (CDs), followed by removal of CD and coalescence of the common guest polymers into a blend. In this paper direct insertion probe pyrolysis mass spectrometry (DIP-MS) analyses of polycarbonate (PC), poly(vinyl acetate) (PVAc) and PC/PVAc blends, obtained by coalescence from their inclusion compounds formed with host γ-CD (coalesced blend) and by co-precipitation (physical blend), have been performed. Variations in the thermal stabilities of the coalesced polymers were recorded both by TGA and DIP-MS and compared to the corresponding as-received polymers. It has been determined that for both coalesced and physical blends of PC/PVAc, CH 3COOH formed by deacetylation of PVAc above 300 °C, reacts with PC chains decreasing their thermal stability. This process was more effective for the physical blend, most likely due to enhanced diffusion of CH 3COOH, produced by deacetylation of PVAc, into the PC domains, where it can further react producing low molecular weight PC fragments bearing methyl carbonate chain ends.

Separation by Inclusion: Selectivity by Tetraphenylethanediol of Toluene and Mono-halo Substituted Benzenes

The host 1,1,2,2-tetraphenyl-1,2-ethane diol was found to form inclusion compounds with the guest toluene and three mono-halo substituted benzenes; chloro-, bromo-, and iodo-benzene. These compounds were characterised by thermal analysis, which showed host:guest ratios of 1:1/2, and their structures were elucidated and compared. Two-, three- and four-component competition experiments were conducted to investigate the selectivity of the host for the respective guests and to determine the separation capabilities of this system.

Chromotropic Behavior of Lophine Nitro-Derivatives

The crystal and molecular structures of two novel derivatives of the lophine chromophore with different solvents of crystallization are presented and discussed. Phenol, 2-[4,5-bis(4-methoxyphenyl)-1H-imidazole-2-yl]-4-nitro (1) and phenol, 2-[4,5-bis(4-methyl-phenyl)-1H-imidazole-2-yl]-4-nitro (2) form inclusion compounds with various guest molecules. The guest molecules interconnect host molecules of 1 and 2 through hydrogen bonds. The inclusion compounds showed chromotropic properties upon trituration, heating, or using different solvents for crystallization. The thermochromic properties have been determined by the removal of the guest molecules. To clarify the relations between the color, thermochromic properties, and the role of host in crystal packing, we have determined and compared a single-crystal X-ray analysis of six crystal structures of the two compounds. Thermal behavior in the solid state and spectroscopic behavior at different pH values and at various solvents are presented and discussed.

Inclusion properties of quinolines by a diol host compound

1,4-bis(9-hydroxyfluoren-9-yl)benzene (H) is a versatile host compound which conforms to EdwinWeber’s host design specifications in that the molecule is rigid and bulky and contains hydroxyl moieties, which are good hydrogen-bond donors. In literature, this compound has been employed for the separation of the isomers of lutidine [1] and for the guest exchange between acetone and DMSO . The guest selectivity between aniline and benzylamine by this host has been studied and was found changed dramatically by controlling PH . In this study we investigate the inclusion properties of the host compound towards quinoline(Q), 2-methylquinoline (2MeQ), 6-methylquinoline (6MeQ) and 8-methylquinoline (8MeQ) ( see Scheme). All the guests formed inclusion compounds with the same host:guest ratio. Single x-ray crystal structures of the inclusion compounds have been elucidated and are all stabilised by (host)O-HcccN(guest) hydrogen bonds. Thermal stabilities were studied by Thermogravimetry (TG). Competition experiments were carried out to study the guest selectivity.

Complexation with diol host compounds. Part 36: inclusion compounds of 1,1,6,6-tetraphenylhexa-2,4-diyne-1,6-diol with benzene, toluene and mesitylene

The title compound 1,1,6,6-tetraphenylhexa-2,4-diyne-1,6-diol (H) forms inclusion compounds with benzene, toluene and mesitylene. H·C6H6 (1) and H· $$\frac{3}{4}$$ C7H8 (2) crystallize in the triclinic space group P(-1) with unit cell dimensions for 1: a = 13.001(3) A, b = 15.284(3) A, c = 16.744(3) A, α = 99.26(3)°, β = 74.78(3)°, γ = 64.96(3)°, Z = 4 and for 2: a = 12.922(3) A, b = 15.159(3) A, c = 16.562(3) A, α = 68.12(3)°, β = 73.99(3)°, γ = 66.00(3)°, Z = 4. The hydroxyl groups of adjacent host molecules are involved in hydrogen bonding. H·C9H12 (3) exhibits a different packing arrangement with weak hydrogen bonding between the hydroxyl hydrogen of the host and the phenyl ring of the guest. The crystal system of compound 3 is monoclinic with space group C2/c, a = 23.750(5) A, b = 8.4746(17) A, c = 17.760(4) A, α = 90°, β = 123.40(3)°, γ = 90°, Z = 4. The thermal behaviour of these compounds has also been studied.

High guest inclusion in 3β-amino-7α,12α-dihydroxycholan-24-oic acid enabled by charge-assisted hydrogen bonds

3β-Amino-7α,12α-dihydroxycholan-24-oic acid (2) forms inclusion compounds with high ratio (host/guest=1/4) of guest methanol. Both hydrogen bonds and hydrophobic interactions are important to the solid structure. The cholates assemble in a head-to-tail fashion to form infinite hydrogen-bonded chains. The chains are interconnected between cholates and also through the guests. Large channels are formed along the crystallographic a axis where most of the methanol molecules are located. Presence of a dominant hydrogen-bonding motif (i.e., ammonium-carboxylate ion pairing) is probably responsible for high guest incorporation.

Complex Formation of Cyclodextrins with Various Thiophenes and their Polymerization in Water: Preparation of Poly-pseudo-rotaxanes containing Poly(thiophene)s

Cyclodextrins (α-CD, β-CD and 2,6-di-O-dimethyl-β-CD (DM-β-CD)) were found to form inclusion compounds with thiophenes (thiophene (T), bithiophene (2T)) in water and in crystalline states. The structures of α-CD–T, β-CD–2T, and DM-β-CD–2T inclusion complexes were determined by X-ray crystallography. DM-β-CD forms a 1:1 cage type complex with 2T. In contrast, β-CD formed 2:3 (CD:guest) complexes with thiophene and α-CD formed 2:3 complexes, both of the channel type. These inclusion complexes were found to polymerize by FeCl3 in the inclusion compounds in water. The products were formed poly-pseudo-rotaxane between cyclodextrins and poly(thiophene) characterized by IR, 1H-NMR and 13C CP/MAS NMR. The molecular weights of the poly-pseudo-rotaxanes with poly(thiophene) were determined by the MALDI-TOF mass spectra to be 3000–5000. In comparison between poly-pseudo-rotaxane (DM-β-CD–poly(thiophene)), authentic poly(thiophene) and the washed DM-β-CD–poly(thiophene) which was washed with DMF to dethread DM-β-CD, these poly-pseudo-rotaxane was characterized by Raman, UV–vis and fluorescence spectra. The maximum emission band of DM-β-CD–poly(thiophene) shifted to a shorter wavelength. The hypsochromic shift was derived from poly-pseudo-rotaxane with DM-β-CD.

Silicon Analogues of Triarylmethanol Hosts. Inclusion Properties and Host–guest Structures: A Comparative Study

The simple triarylmethanol hosts, 2 and 4, and their silicon analogues, 1 and 3, have been studied for comparison of the formation of crystalline inclusion compounds. Clathrate formation experiments showed that replacement of the carbinol C atoms in 2 and 4 by Si atoms to give 1 and 3 resulted in a distinct increase of the capability to form inclusion compounds with organic guests, in particular with alcohols. Moreover, the naphthyl derivatives are much more efficient than the phenyl species, irrespective of the carbinol and silanol features. In order to investigate and compare the guest recognition modes and packing relations of hosts 1–4 in their crystalline inclusion compounds, 11 selected co-crystals, namely 1·DMSO (2:1), 3·EtOH (1:1), 3·i-PrOH (1:1), 3·acetone (1:1), 3·DMSO (1:1), 3·THF (1:1), 3·piperidine (1:1), 4·acetone (1:1), 4·DMSO (1:1), 4·1,4-dioxane (1:1) and 4·benzene (1:1), were studied by X-ray diffraction from single crystals. The survey contains additional 11 crystal structures from the literature and provides a detailed discussion of isostructurality relationships.

Self-assembly Characterization of the β-Cyclodextrin and Hydrochlorothiazide System: NMR, Phase Solubility, ITC and QELS

Supramolecular self-assembly formed by \(\beta\)-cyclodextrin ( \(\beta\)-CD) and hydrochlorothiazide (Htz) was characterized in two aspects: (1) Short distance host–guest interactions, by NMR techniques such as 1H chemical shift, longitudinal relaxation times – T 1, 2D 1H–1H nuclear Overhauser spectroscopy, and thermodynamic solubility experiments in which the interaction thermodynamic parameters were calculated for host–guest interactions and (2) Self-assembly of inclusion complex, which was observed in excess of CD by isothermal titration calorimetry and quasi-elastic light scattering. In this work, the self-assembly of Htz and \(\beta\)-CD occurred above the concentration of ≈10−4 mM. This phenomenon was verified when excess of \(\beta\)-CD was used in the presence of the higher hydrogen bonding formation molecule as Htz. At lower CD molar ratio the inclusion compound formation is the preferential phenomenon. Thus the Htz seems act as a seeding molecule capable of inducing the self-assembly phenomena, through hydrogen bonding formation between the inclusion compounds.

Preparation and Characterization of the Solid Inclusion Compounds of α-, β-Cyclodextrin with Phenylalanine (D-, L- and DL-Phe) and Tryptophan (D-, L- and DL-Trp)

The solid cyclodextrin (α-, β-CD) inclusion compounds of phenylalanine (D-, L- and DL-Phe) and tryptophan (D-, L-␣and DL-Trp) were prepared and the stoichiometry of host and guest in the supermolecules was determined to be 1:1 based on elemental analyses. β-CD formed inclusion compounds with α-aromatic amino acid (α-AAA) in higher yield in contradistinction to α-CD. The yields of the α- or β-CD inclusion compounds of a pair of optical isomers of chiral aromatic amino acids and their racemic modification decreased in the order L->DL->D-form. The complexation between CD and α-AAA caused a change in shape, location and diffracted intensity of the X-ray diffraction peaks of both host and guest. The decomposition temperature of the inclusion compounds was not only slightly higher than that of a pure host but also remarkably higher than that of a pure guest. Upon inclusion the signals of CD protons inside the cavity shifted to upfield while those of the protons outside the cavity had only smaller changes, and the proton signals of the aromatic ring of guest shifted to a certain extent. The chemical shift changes of 4-H and 5-H located in small end side of cavity were a bit bigger than those of 2-H and 3-H located in large one, suggesting that aromatic ring of a guest molecule within a host cavity might be kept near small end side of␣cavity. An ESI-MS experiment has proved the formation and stability of the 1:1 CD inclusion compounds of α-AAA in aqueous solution.

Specific Inclusion Mode of Guest Compounds in the Amylose Complex Analyzed by Solid State NMR Spectroscopy

The inclusion compound formation between linear amylose of molecular weight 102500 (AS100) and p-aminobenzoic acid (PA) during the sealed-heating process was investigated by powder X-ray diffractometry, infrared spectroscopy and solid state NMR spectroscopy. Sealed-heating of AS100 and PA at 100 degrees C for 6 h provided an inclusion compound with 6(1)-helix structure, while a 7(1)-helix structure was found when sealed-heating was carried out at 150 degrees C for 1 h. The formation of an inclusion compound was not observed when sealed-heating was performed at 50 degrees C for 6 h. The 7(1)-helix inclusion compound maintained its structure even during storage at high temperature while the 6(1)-helix inclusion compound decomposed and returned to the original V(a)-amylose upon heating to 180 degrees C. Quantitative determination revealed that one PA molecule could be included per one helical turn of AS100 for both 6(1)-helix and 7(1)-helix inclusion compounds. Solid state NMR spectroscopy suggested that PA molecules were included in the amylose helix core in the 7(1)-helix inclusion compound, while in the case of 6(1)-helix inclusion compound, PA molecules were accommodated in the interstices between amylose helices. Moreover, the inclusion compound formation by sealed-heating of AS100 was also observed when using PA analogues as guest compounds. The binding ratio of AS100 and PA analogues varied depending on the size of guest molecules.

Solid-state hydrogen bonded assembly of N,N′-bis(glycinyl)-pyromellitic diimide with aromatic guests

The compound N,N′-bis(glycinyl)pyromellitic diimide (L) forms inclusion compounds with aromatic hydrocarbons such as anthracene (D1), phenanthrene (D2) and perylene (D3) as well as tetrathiafulvalene (D4). The aromatic guest molecules are held in the spaces between the aromatic units of extended self-assembly of L derived from the hydrogen bonding between the carboxylic acid end groups of L. The crystal structures of each of these inclusion compounds are determined along with the parent compound L. A R44(12) hydrogen bond pattern involving the carboxylic groups and two bridging methanol molecules is observed in the anthracene inclusion compound of L, whereas in the case of other inclusion compounds conventional R22(8) type hydrogen bonding is observed. While forming inclusion compounds of L with tetrathiafulvalene, the carboxylic acid of L has R22(8) and C11(3) types of hydrogen bonding patterns in the lattice. Preferential inclusion compound formation of L with anthracene over isomeric phenanthrene is observed.

Inclusion of volatile guests by a tetrapedal host: structure and kinetics

The host compound tetra(3-hydroxy-3,3-diphenyl-2-propynyl)ethene, TET, forms inclusion compounds with acetone, dimethyl sulfoxide, dioxane and pyridine. All the structures were successfully solved in the triclinic space group P1[combining macron]. We found variable host : guest ratios for the acetone (TET.ACE, H : G = 1 : 4), dimethyl sulfoxide (TET.DMSO, H : G = 1 : 4) and pyridine compounds (TET.PYR, H : G = 1 : 5). Solutions of the host compound and dioxane formed TET.2DIOX, H : G = 1 : 2 when left to crystallise at room temperature, whereas TET.4DIOX, H : G = 1 : 4 was formed during crystal growth at low temperature. We have correlated the structures with their thermal stabilities and kinetics of desolvation.

A Supramolecular Complex between Proteinases and ??-Cyclodextrin that Preserves Enzymatic Activity

Cyclodextrins are suitable drug delivery systems because of their ability to subtly modify the physical, chemical, and biological properties of guest molecules through labile interactions by formation of inclusion and/or association complexes. Plant cysteine proteinases from Caricaceae and Bromeliaceae are the subject of therapeutic interest, because of their anti-inflammatory, antitumoral, immunogenic, and wound-healing properties. In this study, we analyzed the association between beta-cyclodextrin (betaCD) and fraction P1G10 containing the bioactive proteinases from Carica candamarcensis, and described the physicochemical nature of the solid-state self-assembled complexes by Fourier transform infrared (FTIR) spectroscopy, thermogravimetry (TG), differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), and nuclear magnetic resonance (NMR), as well as in solution by circular dichroism (CD), isothermal titration calorimetry (ITC), and amidase activity. The physicochemical analyses suggest the formation of a complex between P1G10 and betaCD. Higher secondary interactions, namely hydrophobic interactions, hydrogen bonding and van der Waals forces were observed at higher P1G10 : betaCD mass ratios. These results provide evidence of the occurrence of strong solid-state supramolecular non-covalent interactions between P1G10 and betaCD. Microcalorimetric analysis demonstrates that complexation results in a favorable enthalpic contribution, as has already been described during formation of similar betaCD inclusion compounds. The amidase activity of the complex shows that the enzyme activity is not readily available at 24 hours after dissolution of the complex in aqueous buffer; the proteinase becomes biologically active by the second day and remains stable until day 16, when a gradual decrease occurs, with basal activity attained by day 29. The reported results underscore the potential for betaCDs as candidates for complexing cysteine proteinases, resulting in supramolecular arrays with sustained proteolytic activity.

Loading of porous metal–organic open frameworks with organometallic CVD precursors: inclusion compounds of the type [LnM]a@MOF-5

The highly porous coordination polymer [Zn4O(bdc)3] (bdc = benzene-1,4-dicarboxylate; MOF-5 or IRMOF-1) was loaded with typical MOCVD precursor molecules 1–10 for metals such as Fe, Pt, Pd, Au, Cu, Zn, Sn. Exposure of [Zn4O(bdc)3] to the vapour of the volatile organometallic compounds, e.g. ferrocene (3), resulted in the formation of inclusion compounds of the type [LnM]a@MOF-5, where [LnM] indicates the MOCVD precursor and a denotes the effective number of molecules per cavity of the MOF-5 lattice. The obtained inclusion compounds were characterised by C/H combustion analysis, determination of the metal content by atomic absorption spectroscopy, FT-IR and solid state NMR spectroscopy and by powder X-ray diffraction. The data prove that the host lattice and the guest molecules interact only by weak van der Waals forces without any change of the framework or the chemical nature of the included molecules. Rapid desorption is observed for small and comparably volatile compounds such as pentacarbonyliron or diethyl zinc. Less labile inclusion compounds were obtained for cyclopentadienyl complexes as guest molecules, e.g. a rather high loading of six molecules of ferrocene per cavity was observed. Careful hydrolysis/calcination of [Zn(C2H5)2]2@MOF-5 resulted in the composite (ZnO)2@MOF-5 pointing to the possibility to develop a subsequent chemistry of the embedded precursor molecules to yield novel nanocomposite materials based on MOFs as host matrices and MOCVD precursors in general.