A model of the primary process in photosynthesis

The arrangement of membrane-bound pigments, proteins, and lipids in the thylakoids of higher plants is described, and the role of the membrane in preventing the back-reaction is discussed. The photosynthetic bacterium halobacterium halobium is also described. A simplified quantum-mechanical picture of the primary process in photosynthesis is presented, and the mechanism of electron-hole separation in this picture is compared with the corresponding mechanism in a silicon solar cell. An appendix discusses the application of Frenkel exciton theory to the antenna effect.     

Syntheses in the quinoline series

2-Formyl-8-hydroxyquinoline and 5,7-dimethyl-2-formyl-8-hydroxyquinoline derivatives were synthesized. The use of nitrophenols as the oxidizing agents in the reaction of the appropriate aminophenols with crotonaldehyde leads to a substantial increase in the yields of quinaldines. According to the IR spectroscopic data, the oximes of the formylhydroxyquinolines have a syn configuration.See [1] for communication II.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 235–239, February, 1978.     

Syntheses in the pyridine series

The conditions for obtaining some -dialkylaminoethyl pyrid-4-yl sulfide N¹-oxides and their quaternary salts have been studied. It has been shown that the addition of alkyl iodides to the bases obtained takes place in a similar manner to their addition to pyrid-4-yl sulfides not containing a N-oxide group.For part VII see [1]     

Syntheses in the phenothiazine series

2,3-Dihydrothiazolo[4,5-b]phenothiazine-2-thione was obtained by the reaction of 2-amino-phenothiazine with sulfur and carbon disulfide, and the action of alkyl halides on it was studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 42–44, January, 1971.See [1] for communication XXVIII.     

Syntheses in the phenothiazine series

Some nucleophilic substitution reactions of 2-methylmercapto-3-methylthiazolo[4,5-b]phenothiazinium methosulfate were studied. Cleavage of the latter with alcoholic alkali gives bis(2-2-methylamino-3-phenothiazinyl) disulfide; cleavage and subsequent alkylation gives new disubstituted phenothiazines.     

Syntheses in the phenothiazine series

3-Aminophenothiazine is synthesized by hydrazinolysis of 3-phthalimidophenothiazine, prepared by thionating 4-phthalimidodiphenylamine. The structure of the compound is confirmed by preparation of derivatives.For Part XVIII see [1]     

Syntheses in the pyridine series

A new procedure for preparing 2-methyl-6-methoxy-4-thioquinolone (I), 2-methyl-7-chloro-4-thioquinoline (II), 2-thiopyridone (III) and 5-nitro-2-thiopyridone (IV) has been proposed. This involves the reactions of the corresponding halogen derivatives of quinoline and pyridine with sodium thiosulfate. Compounds I and II were synthesized for the first time.     

Syntheses in the pyridine series

It has been shown that when they are heated in 2 N caustic soda solution alkyl pyrid-2-yl sulfides are hydrolyzed at the Py-S bond with the formation of pyridones and the corresponding thiols. The latter were determined quantitatively by iodometric titration.For part VIII, see [1].     

Syntheses of conformationally constricted molecules as potential NAALADase/PSMA inhibitors

Two six-membered ring targeted analogues of PSMA inhibitors (4a and 4b) were designed on the basis of a computational analysis and synthesized. (E,Z)-Diene 10 was subjected to the nitroso Diels-Alder reaction to give the 1,4-trans six-membered ring adduct, 4a. The cis isomer 4b was derived from similar nitroso cycloaddition reactions with the corresponding (E,E)-diene and separately from cyclohexadiene. The IC(50) values of 4a and 4b in a NAALADase assay were found to be 0.9 and 0.1 microM, respectively. [reaction: see text]     

A simulation of key aspects of a primary process in natural photosynthesis by a Langmuir-Blodgett film assembly

An advanced Langmuir-Blodgett (LB) assembly designed to replicate the three key aspects (antenna, reaction center, and quinone pool) of a primary process in natural photosynthesis was successfully fabricated by alternate deposition of a mixed monolayer of an artificial reaction center and an antenna pigment and a pure bilayer of a second donor.     

Synthesis of new 1,2,3-triazole linked benzimidazole molecules as anti-proliferative agents

One pot click chemistry is used to link triazole and benzimidazole pharmacophore to get N-((1-((1H-benzo[d]imidazol-2-yl)methyl)-1H-1,2,3-triazol-4-yl)methyl)aniline and its derivatives. Flexible linkages in the form of –CH₂–R or –O–R/–N–R were designed during synthesis. All the newly synthesized compounds were characterized by FT-IR and NMR spectroscopy as well as high-resolution mass spectrometry. Selected compounds were screened for in vitro anti-proliferative activity using National Cancer Institute (NCI)-60 human tumor cell line screening program. The most potent structure N-((1-((1H-benzo[d]imidazol-2-yl)methyl)-1H-1,2,3-triazol-4-yl)methyl)-4-chloroaniline 7e showed 40% growth inhibition in renal cancer cell line (UO-31) at 10?µM concentration.     

Photochemistry of porphyrins: a model for the origin of photosynthesis

A series of porphyrins and catalysts has been prepared as a model for the origin of photosynthesis on the primordial earth. These compounds have been used to test the hypotheses that (1) the biosynthetic pathway to chlorophyll recapitulates the evolutionary history of photosynthesis, and (2) the proto-photosythetic function of biogenetic porphyrins (biosynthetic chlorophyll precursors) was the oxidation of organic molecules by photoexcited porphyrins with the attendant emission of molecular hydrogen. This paper describes experiments in which photoexcited biogenetic porphyrins oxidize ethylenediamine tetraacetic acid (EDTA). The concomitant reduction of protons to hydrogen gas occurs in the presence of a colloidal platinum catalyst. The addition of methyl viologen, a one-electron shuttle, increases the amount of molecular hydrogen generated during long irradiations and the quantum yield of hydrogen production. When the porphyrin and catalyst are held in association by molecular complexes, the increased efficiency of electron transfer produces higher yields of hydrogen gas.     

Syntheses of halogenated ethenyl isocyanide chromium complexes as organometallic precursor molecules for ethenyl and ethynyl isocyanides

The radical alkylation of tetraethylammonium pentacarbonyl(cyano)chromate 1 yielded the halogenated ethyl isocyanide complexes [(CO)5Cr(CN-CClX-CClYF)] 3 (a, X= Cl, Y= F; b, X = F, Y= F and c, X=Y= Cl). Dehalogenation of 3 using zinc in diethyl ether gave [(CO)5Cr(CN-CX=CFY)] 4. The compounds 4a, b reacted with various nucleophiles exclusively at the difluoromethylene group. The unstable phosphorane 5, which is formed on reaction of 4b with trimethylphosphane, decomposed thermally and on hydrolysis yielding pentacarbonyl(1,2-difluoroethenyl isocyanide)chromium (6). The cyano substituent can be introduced in the beta position of the isocyanide function by reaction of 4a, b with potassium cyanide, leading to the formation of [(CO)5Cr(CN-CX=CF-CN)] (7). Reactions of 4a, b with organolithium or organomagnesium compounds yielded [(CO)5Cr(CN-CX=CF-R)] (8) and [(CO)5Cr(CN-CF=CF-C...C-CF=CF-NC)Cr(CO)5] (10). The trimethylsilyl group in 8a, b, d could be removed by a solution of potassium carbonate in methanol leading to [(CO)5Cr(CN-CX=CF-Cn-H)] (11) (n=2,4). Octacarbonyldicobalt reacted with 8e under coordination of the C-C triple bond to the hexacarbonyldicobalt fragment, resulting in the cluster compound 12. The crystal and molecular structure of 8i, 11 a, b, and 12 were elucidated by X-ray crystallography. The alkenyl and alkynyl isocyanides CN-CCl=CF2 (13a), CN-CF=CF2 (13b), CN-CCl=CClF (13c), CN-CF=CFH (14), CN-CC-H (15), CN-CC-CN (16), and CN-CCl=CF-CN (17) were obtained by flash vacuum pyrolysis of 4a, 4b, 4c, 6, and 7a, respectively.     

Syntheses based on aldehydes of the thiophene series

Summary The use of 2,5-thiophenedicarboxaldehyde monoacetal in synthesis makes it possible to prepare unsymmetrical bifunctional thiophene derivatives.This article is published in accordance with a resolution of the Conference of Chief Editors of Journals of the Academy of Sciences of the USSR, July 12, 1962, as a dissertation paper by V. I. Rogovik.     

Librational model for the direct spin—lattice relaxation process in isolated triplet molecules in a naphthalene-mixed crystal

For the spin-lattice relaxation (SLR) in molecular crystals a model is presented, which attributes the SLR mechanism to phonon-stimulated molecular librations. Its applicability to the direct process is shown by comparison with the experimental data on quinoxaline guest molecules in a perdeuterated napthalene host crystal.     

Sulfur‐linked Phenolates as Ligands for the Syntheses of Low‐Nuclearity Iron(III) Complexes

Exploiting thiacalix 4 arene and sulfur‐bridged bisphenolates as ligands for bioinorganic studies involving iron(III) requires the prior development of synthetic routes (varying substituents and reaction conditions) to construct complexes with low nuclearities and accessible coordination sites, which was in the focus of this investigation. Treating p‐tert‐butylthiacalix 4 arene (H₄TC) and 1, 4‐dimethyl‐p‐tert‐butylthiacalix 4 arene (Me₂H₂TC) with Fe[N(SiMe₃)₂]₃ yielded in the formation of the iron(III) complexes [(Me₃SiTC)₂Fe₂] ( 1 ) and [(Me₂TC)₃Fe₂] ( 3 ), respectively. While 1 is a sandwich compound, in 3 one [Me₂TC]^2– unit is bridging two [Me₂TCFe]⁺ moieties. Employing thiobisphenolates as ligands it turned out, that in dependence on the residues R and the preparation method it is possible to selectively access sandwich, anionic or neutral complexes, which were shown to contain central high‐spin iron(III) atoms. The syntheses, structures, and electronic properties of three iron(III) bisphenolate complexes, [^ClL₂Fe]NEt₃H ( 4 ), [^MeLFeCl₂]NEt₃H ( 5 ), and [^tBuLFeCl(thf)] ( 7 ) are discussed.     

Theoretical investigation of two-photon absorption properties for a series of bifluorene molecules

The two-photon absorption (TPA) cross-sections of a series of bifluorene molecules with different substituents (constructing three types of structures D–π–D, A–π–A and D–π–A) were calculated using ZINDO/SOS program. The results showed that the A–π–A structure with strong substituent-nitro had the largest TPA cross-section for these molecules. To verify the results, we analyzed the charge quantity of the ground and the main excited states as well as the frontier orbitals of the investigated molecules. The equilibrium geometries were obtained with AM1 method, and using ZINDO-SOS to calculate the third-order nonlinearities of the molecules, then gained the TPA cross-sections. We found that for the compounds with bifluorene as π center, the donor and acceptor strength are the important factor for the enhancement of the TPA properties, and compared with molecules with fluorene as π center, the large TPA cross-sections of bifluorene are caused by coupling effects between the two monomers.