Photochromic properties and reaction mechanism of naphthopyran

The photochromic properties and reaction mechanism of title compounds have been examined with steady method on compounds 3-phenyl-3-[3-methylbenzothiophene-2-yl]-3H-naphtho[2,1-b]pyran (1) and 3-phenyl-3-[benzofuran-2-yl]-3H-naphtho[2,1-b]pyran (2) and nanosecond laser flash photolysis techniques on compound 3-phenyl-3-[1,2-dimethylindol-3-yl]-3H-naphtho[2,1-b]pyran (3). The influence of oxygen on transient spectra and decay kinetics of compound 3 has been investigated. Both excited singlet state and triplet state are involved in the photochromic mechanism of compound 3. The influence of molecular structure on photochromic behavior has been studied also. Decay kinetics indicated that the lifetime of colored forms of 1 and 2 were several orders of magnitude longer than that of 3.     

Synthesis and photochromic properties of substituted naphthopyran compounds

A group of 3,3-diaryl-3H-naphtho[2,1-b]pyran compounds with functional substituents at the 5- and 6-positions of the naphthopyran skeleton and the para positions at the 3-aryl moieties were prepared through condensation reactions between 2-naphthol derivatives and 1,1-diarylprop-2-yn-1-ol derivatives. The chemical structures of the compounds were confirmed by NMR and MS. The crystal structure of 3,3-diphenyl-6-morpholino-3H-naphtho[2,1-b]pyran (4b) was determined and the relationship between the pyran substructure and photochromism was discussed. The photochromic properties were studied as well, and decoloration kinetics of colored forms was fitted to the biexponential model. Among these compounds, 4b was considered to be the best one due to the large ΔOD of colored form, which is one of the most important properties used in the photochromic material.     

Photochromic organic compounds for optical memory

For the purpose of target syntheses of new photochromic compounds, a relationship between the structure and properties of a series of the known thermally irreversible photochromes was analyzed using the spectral kinetic data obtained by the authors. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 853–861, April, 2008.     

Photochromic characteristics of spirocyclic organic and coordination compounds

Methods for the structural modification of photochromic spirocyclic systems (derivatives of spirobenzopyrans, spiro-1,3-oxazines, spiropyrimidines, and the bischelate complexes of nontransition metals), optimizing their spectral, kinetic, photochemical, and other characteristics in the direction required for their application as quick-acting chemical memory elements and in optical computers, are examined.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 31, No. 3, pp. 166–180, May–June, 1995.     

Photochromic fulgides based on 2-acetyl-1-methylindole

Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 856–857, June, 1989.     

Photochromic fulgides based on 1-methyl-2-formylindole

The reactions of 1-methyl-2-formylindole with the diethyl esters of alkyl- and phenylmethylene-substituted itaconic acids led to the production of photochromic fulgides, which formed deeply colored 5,8b-dihydrocarbazole derivatives during UV irradiation. It was found by PMR that the fulgides also undergo E,Z isomerization during UV irradiation.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 907–910, July, 1989.     

基于分子指纹对黄酮类化合物及其抗DPPH自由基活性的QSAR分析

应用定量构效关系（Quantitative structure activity relationship, QSAR）研究阐明黄酮类化合物（Flavonoid compounds, FCs）的子结构指纹（Substructure fingerprint）与1,1-二苯基-2-三硝基苯肼（1,1-Diphenyl-2-picrylhydrazyl, DPPH）自由基清除能力之间的关系,从而指导高效抗氧化物质的设计和发现。在PubMed数据库中收集77个具有明确抗氧化活性的黄酮类化合物,而在ChEMBL数据库中收集86个无抗DPPH活性的黄酮类化合物。这163个黄酮类化合物的子结构指纹由PubChem系统生成,然后通过卡方检验筛选出与黄酮类化合物的抗氧化活性显著相关的分子指纹,最后通过判别分析建立预测QSAR模型,并采用回代法和交叉验证法对已建立的模型进行准确性和稳健性的验证。结果表明,黄酮类化合物抗DPPH自由基活性与ESSSR环的计数、简单相邻原子的类型和简单的SMARTS模式等因素有关。此外,所建立的QSAR模型能较好地预测黄酮类化合物的DPPH自由基清除活性,可用于评价候选抗氧化剂的潜力。     

New routes to organofluorine compounds based on ketenes and the radical transfer of xanthates

New routes to organofluorine derivatives based mostly on the powerful xanthate radical transfer technology are described. A special emphasis is placed on the synthesis of trifluoromethyl-substituted structures, including trifluromethyl ketones and fluorinated aromatic and heteroaromatic substances of interest to the pharmaceutical and agrochemical industries.     

Photochromic ordered mesoporous hybrid materials based on covalently grafted polyoxometalates

Novel polyoxometalate (POM)-grafting mesoporous hybrid silicas, XW(11)/MHS (X=P, Si) and TBAPW(11)Si(2)/MHS, have been prepared respectively by co-condensation and post-synthesis routes based on the employment of Keggin-type monovacant XW(11) or a Si-substituted compound TBAPW(11)Si(2) as POM precursors. Upon characterization of the samples by FT-IR, XRD, ICP-AES, TEM and N(2) adsorption-desorption measurement, it was found that Keggin units were retained perfectly in ordered hexagonal mesopore channels with SBA-15 architecture and immobilized by covalent linkages on the mesopore wall. These materials, especially the co-condensed samples, exhibited stable and reversible photochromic properties under UV irradiation although no special organic component was supplied additionally as an electron donor. An investigation of the photochromism revealed that the photochromic response depended on the centre atom of the POM species (i.e., the redox potential of the POM), the content of the POM and the synthetic route of the sample, while the bleaching process was correlated not only to the redox potential but also to the pore size of the sample. The photochromic mechanism was also studied in detail by cyclic voltammetry, ESR, FT-IR and XPS techniques. It was found that the remaining P123 template acted as a reducing agent and was oxidized during the photochromic process accompanied by the reduction of the POM to heteropolyblue. Thus, a close contact between the POM and the remaining P123 chain in the sample is necessary. Low close-contact degree results in poor photochromic behavior of the post-synthesized sample and impregnated samples.     

Complex compounds based on a colchicine derivative

Complex compounds based on deacetyl-10-ethanolamino-10-demethoxycolchicine with Co, Mn, and Fe chlorides have been obtained, and their radiomodifying and antitumoral properties have been investigated.Tashkent State University, 700095, Tashkent, CIS, Vuzgorodok. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 728–730, September–October, 1996. Original article submitted November 5, 1994; revision submitted April 7, 1995.     

Benzopentalenonaphthalenones from the intramolecular capture of a merocyanine derived from a naphthopyran

Novel, highly coloured benzopentalenonaphthalenones result from a cascade process initiated by the thermally-induced ring-opening of diarylmethanol substituted 2H-naphtho[1,2-b]pyrans in the presence of acid.     

Experimental and theoretical investigations of cyanide detection using a photochromic naphthopyran

Photochromic naphthopyran derivatives were synthesised for anion recognition applications. The crystal structure, experimental and theoretical investigation of photochromic and anion sensing properties of a simple naphthopyran derivative were investigated. The naphthopyran derivative displayed good fatigue resistance and selective sensing response towards cyanide ions. The mechanism of complex formation was suggested based on NMR studies. Theoretical calculations were performed to understand the experimental results. An excellent correlation between the theoretical and experimental data was observed.     

Spectrokinetic studies on new bi-photochromic molecules containing two naphthopyran entities

A range of new bi-photochromic molecules containing two identical (3a-d) or two distinct naphthopyran units (6a-d), linked through the phenyl substituents located on the sp³ hybridised pyran ring carbon atom, using conjugated and non-conjugated spacers, have been synthesised from bis-propynols and (substituted)naphthols. Study of the spectrokinetic properties of these compounds under near UV-vis continuous irradiation conditions revealed that the two naphthopyran units are stimulated independently leading to open forms with higher colourabilities but without affecting the individual bleaching kinetics. Compared to the individual photochromic components and to model mono-photochromes it was observed that the nature of the bridge has a small effect on the photochromic properties of each system.     

Photoinduced switching from living radical polymerization to a radical coupling reaction mediated by organotellurium compounds

An efficient and simple method for the synthesis of symmetric macromolecules by photoinduced switching from radical polymerization to a radical coupling reaction is reported. Structurally well-defined telechelic polyisoprenes and ABA-triblock copolymers were prepared by successive organotellurium-mediated living radical polymerization (TERP) under thermal conditions, followed by a polymer-end radical coupling reaction under photoirradiation.     

Alkyl radical hyperconjugation in phosphorus compounds

Conclusions The³¹P and¹⁹F chemical shifts in phosphorus compounds of various conformations vary with the number of hydrogen or fluorine atoms attached to the-C atom of the phosphorus atom alkyl or perfluoroalkyl radical. This effect can be explained in terms of alkyl radical hyperconjugation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2435–2439, September, 1976.     

Photochromic soft materials: flavylium compounds incorporated into pluronic F-127 hydrogel matrixes

The performance of flavylium-based photochromic systems is increased by their incorporation into Pluronic F-127 matrixes, which switch from polymeric solutions to micelles to gels with changes in temperature depending on copolymer concentration. Two flavylium compounds, 7,4'-dihydroxyflavylium and 7-(N,N-diethylamino)-4-hydroxyflavylium, both exhibiting a small thermal cis-trans isomerization barrier in water were investigated. In the first system the flavylium in the gel photoswitches from the colorless trans-chalcone (Ct) species to the yellow flavylium cation (AH+) with quantum yield Phi=0.04 (25 degrees C) at pH 2.2 or to the orange quinoidal base (A) with quantum yield Phi=0.015 (25 degrees C) at pH 5.2. The photoproducts revert back to their initial form by a thermal process characterized by first-order kinetics; the rate constants exhibit a bell shape variation with pH, with a maximum at pH 4.3 (lifetime 4.2 min). The second system, 7-(N,N-diethylamino)-4-hydroxyflavylium, does not exhibit photochemistry in water but, when incorporated into the Pluronic F-127 gel, switches from yellow to red with a quantum yield of Phi=0.01 at pH 4.9. The respective thermal back reaction takes place with a lifetime of 66.7 min1. The flavylium network of chemical reactions is a good sensor for the detection of not only the critical micelle temperature but also the gelation temperature of Pluronic and like solutions and, in some instances, the exposure to UV and visible radiation.     

Films based on a solid solution of CdS-ZnS system from thiourea coordination compounds and their properties

The patterns of the formation of continuous or discontinuous solid solutions were established a CdS-ZnS system depending on the nature of initial complexes and the deposition temperature. An effect of the nature of a precursor and synthesis temperature on optical, electrical, and luminescent properties of films of the CdS-ZnS system was examined. The correlation between the chemical nature of the ccordimation precursors and phase composition of the films of CdS-ZnS, obtained by spray pyrolysis of solutions of thiourea coordination compounds was detected in a temperature range of 350–500°C.     

Photochromic inorganic-organic multilayer films based on polyoxometalates and poly(ethylenimine)

Novel photochromic inorganic-organic multilayers composed of polyoxometalates and poly(ethylenimine) have been prepared by the layer-by-layer (LbL) self-assembly method. The growth process, composition, surface topography, and photochromic properties of the multilayer films were investigated by UV-visible and Fourier transform infrared spectroscopy, atomic force microscopy, electrospin resonance (ESR), and X-ray photoelectron spectroscopy (XPS). Irradiated with ultraviolet light, the transparent films changed from colorless to blue. Moreover, the blue films showed good reversibility of photochromism and could recover the colorless state gradually in air, where oxygen plays an important role in the bleaching process. On account of the ESR and XPS results, parts of W6+ in multilayers were reduced to W5+, which exhibited a characteristic blue; a possible photochromic mechanism can be speculated. This work provides basic guideline for the assembly of multilayers with photochromic properties.