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The photoreaction of metal-organic compounds prepared by the chemical modification of metal alkoxides was investigated for the patterning of ceramic films. The chemical stability and photoreactivity of these compounds were found to be greatly influenced by the kind of chemical additive applied during the syntheses of the precursor solutions. In this study, the photoreaction of the precursor thin films prepared by the addition of alkanolamines was achieved by tuning the wavelength of the incident UV light. The decomposition of the organic moieties of the percursors was clearly observed in IR spectra during UV irradiation. Furthermore, the spectrum of the titania precursor film in the visible and ultraviolet regions (UV-vis) changed in accordance with the irradiation time. The photolithography of the titanium precursor pattern was successfully achieved by means of these techniques.

Metallo-organic compounds were synthesized for the preparation of tin oxide fine patterning via the addition of alkanolamines. Tin(IV) isopropoxide was chemically modified with diethanolamine (DEA) and/or N-phenyl-diethanolamine (PhDEA). Then, the chemical stability and photoreactivity of the prepared metallo-organic compounds were compared. A tin precursor solution that was formed via the stepwise additions of both DEA and PhDEA showed good chemical stability in air and efficient photoreactivities under ultraviolet irradiation. The fine patterning of tin oxide was achieved successfully on a substrate, using the precursor solution.

The photochemical cycloaddition of stilbazolium ions intercalated in clay layers has been studied. syn Head-to-tail dimers were predominantly formed at the expense of E–Z isomerization which is a major path in homogeneous solution. The selective formation of head-to-tail dimers suggests that the intercalation occurs in an antiparallel fashion. The dimerization efficiencies were not affected even when the degree of adsorption of alkene molecules on the anionic-exchange site of the clay was decreased from 100 to 1%. The intercalated stilbazolium ions exhibited a strong excimer emission at 490–520 nm in addition to the monomer fluorescence at 380–450 nm. The strong excimer emission was not decreased even at 0.1% adsorption. These facts suggest that the intercalation starts via formation of small aggregates of adsorbate molecules, caused by their hydrophobic attraction. Details of the intercalation and photocycloaddition are discussed.

Irradiation of laurylammonium indene-2-carboxylate 1, a self-associating photoreactive surfactant, gives rise to stereoselective formation of syn-2 and anti head-to-head dimers 3 depending upon the choice of solvent.

1′,3′,3′-Trimethylspiro[2H-1-benzopyran-2,2′-indoline](abbreviated to H–SP) and its derivatives, 6-nitro (NO2–SP) and 6-nitro-8-(pyridinium)methyl spiropyrans (Py+–SP), have been intercalated in the interlayers of Montmorillonite. The intercalation was highly dependent on the substituent groups on the SPs. Charged Py+–SP was quantitatively adsorbed on the clay as an equilibrium mixture with the corresponding merocyanine (Py+–MC) in aqueous colloidal solution, the ratio Py+–SP:Py+–MC being 35:65 and exhibiting reversed photochromism. In contrast, a preferential adsorption as Py+–SP was observed for the hydrophobic clay layers coadsorbing cetyltrimethylammonium bromide (CTAB), which displays normal photochromism. The thermal isomerization of Py+–SP intercalated in aqueous colloidal clay exhibited a linear combination of two components of the first-order reactions, while that of the Py+–SP–CTAB coadsorbed system satisfied a single first-order kinetics. The two-component kinetics are explicable in terms of the intervention of at least two different kinds of microscopic environment, e.g. non-polar and polar phases, in the clay interlayers. We also show that the photochemical decoloration of Py+–MC was significantly retarded by the intercalation. All of these results are discussed on the basis of the polarity of the intercalation.

Effect of alkylammonium ions (Cn+) has been studied on the clusterization and photochemical behaviors of γ-stilbazolium (4-(2-phenylvinyl)pyridinium) ion (1) adsorbed on clay interlayers. The aggregates of 1 were shown to be dissociated by the coadsorption of Cn+ with molecular length longer than that of 1. The major photoreaction was changed from cyclodimerization to E–Z isomerization on coadsorbing Cn+’s longer than 1. The efficient excimer emission from intercalated 1 was dramatically reduced by coadsorbing alkylammonium ions. The resulting concentration dependence of excimer emission intensity is nicely simulated by a Monte Carlo method for two-dimensional lattice site models.

Photochemical cycloaddition for several unsaturated carboxylates has been studied in the presence fo hydrotalcite clays. Syn head-to-head cyclodimers were selectively formed in the irradiation of sodium cinnamates intercalated in the dispersed clays. On the other hand, two isomers of syn head-to-head and syn head-to-tail cyclodimers were formed for the case of (phenylethyl)benzoates. The degree fo intercalation was shown to be dependent on teh structures of the carboxylates. W-ray diffraction analyses revealed that the carboxylates are intercalated as monolayer, which suggests and alternatte anti-parallel packing since a clay interlayer possesses two ionic surfaces, top and bottom

Aromatic unsaturated carboxylates such as cinnamate and 2-indenecarboxylate form, in the presence of long-chain alkylammonium ion, short rod-like micelles with an aggregation number of an order of 103 in water and premicelle aggregates including 2–3 surfactant molecules in carbon tetrachloride. It was found that these aggregates undergo efficient and stereoselective photodimerizations. Photoreactions in aqueous rod-like micellar solutions resulted in the predominant formation of anti-head-to-head dimers (anti-HH), while the reaction in small aggregated premicelles yielded thermodynamically least stable syn-head-to-head dimers (syn-HH). The addition of a small amount of methanol to the premicelle aggregate shifted the major product from syn-HH to anti-HH. Control experiments showed that the photoreaction of the corresponding methyl ester afforded mixtures of four isomeric dimers, syn- and anti-HH and HT (head-to-tail), of statistical distribution. These stereochemical selectivities are discussed in terms of the organized olefin orientation and correlated to the results of light scattering and NMR probe techniques.

Ionic olefins are adsorbed on oppositely charged surface consisted either of molecular aggregates of organic surfactants or inorganic clay interlayers. The ionic olefins, i.e., stilbazolium cations and unsaturated aromatic carboxylate anions, undergo efficient and stereoselective photocyclodimerization in the present heterogeneous reaction fields. The reaction pathways are quite different from those in solution, where no cyclodimers formed and, observed is only E-Z photoisomerization. Employed are not only micelle, reversed micelles, and vesicles as organic interface, but also montmorillonite and hydrotalcite clays as inorganic minerals. The stereochemistry of the resulting cyclodimers has been elucidated to be controlled by a number of factors such as orientation of the olefins in the interface of host materials, the density of ionic sites of the interface, and the looseness of the molecular packing of the guests. Mixed intercalation of different kinds of host olefins and ketone resulted in the formation of regioselective cycloadducts depending on the kinds of above mentioned ionic interface.

Stereoselectivity of photocyclodimers of unsaturated carboxylates is shown to be controlled by changing the site distance of clay interlayers.

The photochemistry of trans-cinnamic acid (trans-1) was studied in a cast film of dimethyldioctadecylammonium bromide (2), deposited from aqueous dispersions as a crystalline solid by the spontaneous vaporization of water. UV irradiation of the cast film resulted in a highly selective formation of the syn-Head-to-Head dimer, suggesting a parallel orientation of trans-1 within a bilayer film. Analyses with X-ray diffraction, differential scanning calorimetry, and IR spectra revealed the formation of a bilayer structure of 2 in which the molecules of trans-1 are dissolved to interact with 2 of the polar head groups. The photoreactivity of trans-1 in the cast film was found to be dramatically suppressed by heating at 40—60 °C, which is attributed to an improvement in the crystallinity of the bilayer.

A novel enantioselective photochemical pinacolization utilizing the interlayer spaces of layered double hydroxide (LDH) was investigated. UV irradiation of (+)-4-(α-hydroxy-α-phenyl)methylbenzoate [benzhydrol-4-carboxylate] ions (d-BHA) with 4-benzoylbenzoate ions (BBA) gave rise to the formation of (−)-1,2-bis(4-carboxyphenyl)-1,2-bisphenyl-1,2-ethanediol (l-benzopinacol) in the LDH interlayers. Similarly, l-BHA reacts with BBA to give d-benzopinacol in the LDH. A maximum optical yield of over 60%ee was observed at the initial reaction stage.

This article surveys investigations on stereospecific organic photoreactions utilizing well-organized aggregated structures of molecules formed in the interlayer spaces of inorganic layered host compounds. In the beginning sections, the chemical compositions and structural features of the layered hosts and their unique adsorption properties are described, as well as the aggregated structures of the guest molecules. The later sections describe various organic photoreactions, including [2+2] photocycloadditions, photopolymerization and the photopinacolization of aromatic olefins and/or aromatic ketones, while the stereochemistry of the photoreactions is discussed in relation to the aggregated structures of the guest molecules.

The photochromism of 1,2-bis(2-methyl-3-thiophenyl)perfluorocyclo-pentene bearing two pyridinium substituents at each thiophenyl ring (1) in smectite clay thin films is the subject of the present study. In order to prepare oriented thin films with photochromic characteristics, the hybridization of cationic diarylethene molecules, 1, into the layered clay was carried out, and the structure and photochromic properties of these hybrid materials were investigated. Clay intercalated diarylethene exhibited typical photochromic behavior. Polarized spectroscopic data has confirmed the diarylethenes inside the clay to be present as a tilted monolayer. Although the photochromic efficiency of these hybrid materials gradually decreased upon repeated irradiation with alternative UV and visible light, photochromic degradation could be dramatically improved by the cointercalation of cationic surfactant molecules such as dodecylpyridinium ions.

A stilbazolium cation included in clay interlayers undergoes an efficient and regioselective photocycloaddition to afford a syn head-to-tail dimer with suppression of the cis–trans isomerization.

Chlorination of phenol with N,N-dichlororo-t-butylamine (DCB) in appropriate solvents affording o- and p-chlorophenols exhibits high ortho/para ratio up to >10. Solvents associate with phenolic OH group and interfere with the hydrogen bonding between phenol and DCB tend to decrease both rate of reaction and ortho/para ratio; e.g.

Irradiation of 1,4-diphenyl-5-amino-1,2,3-triazole (1a) gives 4-phenyl-5-anilino-1,2,3-triazole (2a) and the reverse photochemical reaction is possible. Hence, the reaction is reversible, the ratio of 1a : 2a in equibrium being 1.2–1.7, which is different from the ratio 0.33 in the thermal reaction (Dimroth rearrangement). The mechanism is discussed on the basis of spectral data and analogous reactions.

The zinc tetraphenylporphyrin (ZnTPP)- and zinc tetrasodiumtetra(p-sulphonatophenyl)porphyrin (ZnTPPS)-sensitized photodebromination of 2,3-dibromo-3-phenylpropionic acid (1) in the presence of a sacrificial reductant yielding cinnamic acid has been studied in cationic cetyltrimethylammonium bromide (CTAB) micellar solution. The photosensitized electron transfer and the resultant debromination are significantly affected by the solubilizing sites of sensitizer and dibromide (1) in the micelle. The debromination proceeds most efficiently when the anionic sensitizer and (1) are adsorbed on the cationic micellar surface. The overall efficiency is controlled mostly by the back electron transfer rather than the forward one, which is competitive with the subsequent debromination steps. The cationic micellar surface is effective for the electron-transfer debromination when both or either of the sensitizers is anionically charged.

Photo-induced dechlorination of β-benzene hexachloride(β-BHC) in alkaline alcohols has been studied. Benzene is a major product accompanying other minor products such as chlorobenzene, alkoxybenzene, and benzyl alcohols. Their yields vary a great deal depending on the kind of alcohol. The efficiency of reaction and the selectivity of benzene increase in the order : methanol

Irradiation of four 1-aryl-1,2-propanediones (Ia–Id) with over 300 nm light in 2-propanol gives reduction products identified to be the corresponding pinacols or hydrols formed by the reduction at the aroyl (but not acetyl) oxygen. The products from 1-(o-tolyl)-1,2-propanedione (Id) can also be accounted for by the initial hydrogen abstraction from ortho methyl by the aroyl carbonyl oxygen. Their photoreactivities are discussed as regards their electronic emission spectra and triplet configuration.

The effect of colloidal silica on the [Ru(bpy)3]2+-sensitized photochemical cis-trans isomerization of N-methyl-4-β-styrylpyridinium (cis-MSP+) ion induced by one-electron transfer has been studied. An efficient electron-relay chain reaction has been shown to take place on the colloidal surface, on the basis of remarkably high quantum yields compared with those in the absence of colloids. The adsorption of cis-MSP+ on the surface of the colloidal particles is discussed.

Isomerisation cis-trans de chlorure et de iodure de N-methyl β styril-4 pyridinium dans divers systemes micellaires. (λ≃468 nm). L'efficacite de l'isomerisation est grandement amelioree en presence d'agents de surface anioniques. Mecanisme. Effet de l'addition de sels

Die Acrylanilide (I) werden durch UV-Bestrahlung zu den 3,4-Dihydro-caF bostyrilen (II) cyclisiert.