Asymmetrical porphyrins. I. Synthesis,characterization and physicochemical properties of phenyl/4-benzyloxyphenyl 5,10,15,20-substituted porphyrins

A complete series of five phenyl/4-benzyloxyphenyl 5,10,15,20-substituted porphyrin has been synthesized, characterized by analysis, R_f values, and proton-nmr spectroscopy (pmr). Their physicochemical properties, namely ir spectra, absorption spectra, emission spectra, excited state life-times, pK₃ values, reduction potentials, and kinetics of Cu(+2) insertion, have been determined. Attempts have been made to correlate these physicochemical properties with the structures of the porphyrins.     

Synthesis and properties of hyperbranched conjugated porphyrins

[reaction: see text] Hyperbranched conjugated porphyrin arrays were prepared by one-pot Suzuki polycondensation of AB3 and AB3 + C4 approaches.     

Synthesis and physicochemical properties of metallobacteriochlorins

Access to metallobacteriochlorins is essential for investigation of a wide variety of fundamental photochemical processes, yet relatively few synthetic metallobacteriochlorins have been prepared. Members of a set of synthetic bacteriochlorins bearing 0-4 carbonyl groups (1, 2, or 4 carboethoxy substituents, or an annulated imide moiety) were examined under two conditions: (i) standard conditions for zincation of porphyrins [Zn(OAc)(2)·2H(2)O in N,N-dimethylformamide (DMF) at 60-80 °C], and (ii) treatment in tetrahydrofuran (THF) with a strong base [e.g., NaH or lithium diisopropylamide (LDA)] followed by a metal reagent MX(n). Zincation of bacteriochlorins that bear 2-4 carbonyl groups proceeded under the former method whereas those with 0-2 carbonyl groups proceeded with NaH or LDA/THF followed by Zn(OTf)(2). The scope of metalation (via NaH or LDA in THF) is as follows: (a) for bacteriochlorins that bear two electron-releasing aryl groups, M = Cu, Zn, Pd, and InCl (but not Mg, Al, Ni, Sn, or Au); (b) for bacteriochlorins that bear two carboethoxy groups, M = Ni, Cu, Zn, Pd, Cd, InCl, and Sn (but not Mg, Al, or Au); and (c) a bacteriochlorin with four carboethoxy groups was metalated with Mg (other metals were not examined). Altogether, 15 metallobacteriochlorins were isolated and characterized. Single-crystal X-ray analysis of 8,8,18,18-tetramethylbacteriochlorin reveals the core geometry provided by the four nitrogen atoms is rectangular; the difference in length of the two sides is ～0.08 ?. Electronic characteristics of (metal-free) bacteriochlorins were probed through electrochemical measurements along with density functional theory calculation of the energies of the frontier molecular orbitals. The photophysical properties (fluorescence yields, triplet yields, singlet and triplet excited-state lifetimes) of the zinc bacteriochlorins are generally similar to those of the metal-free analogues, and to those of the native chromophores bacteriochlorophyll a and bacteriopheophytin a. The availability of diverse metallobacteriochlorins should prove useful in a variety of fundamental photochemical studies and applications.     

Synthesis and physicochemical properties of melam

Fusing melamine with 2, 4-diamino-6-chloro-s-triazine gives melam. From its UV and IR spectra, it is assigned structure II. Thermographic studies showed that melam is not an intermediate product, but a side product, of thermal deamination of melamine.     

Synthesis and physicochemical properties of cationic starches

The reaction kinetics of an aqueous suspension of potato starch, various amounts of NaOH, and cationic 3-chloro-2-hydroxypropyltrimethylammonium (chloride) were studied in detail. It was found that the compositions of the sparsely substituted cationic starch ethers and the efficiency of the reaction depended strongly on the ratio of components in the alkylating mixture. The physicochemical properties of the synthesized samples were studied using chemical analysis, scanning electron microscopy, x-ray structure analysis, and thermogravimetry. It was shown that the temperature regime of the reaction had a determining influence on the thermal stability and structural changes of the cationic starch derivative.     

Synthesis and physicochemical properties of biomorphic zirconia fibers

Biomorphic zirconia fibers were prepared by successive carbonization and/or calcining of sawdust impregnated by a solution of zirconium oxynitrate. Pyrolysis was performed in nitrogen (500°C), and calcining, in air (600°C). The physicochemical characteristics of samples were studied by adsorption measurements, electron microscopy, and X-ray diffraction. The biomorphic fibers were composed of zirconia nanoparticles not larger than 12 nm. The samples had a uniform phase composition dominated by the tetragonal ZrO₂ phase; their specific surface area was 13–38 m²/g depending on the salt content in sawdust. It was assumed that the stabilization of the tetragonal phase could be related to the incorporation of mineral components (calcium, magnesium, and potassium compounds) of sawdust into zirconia; carbonization had no substantial effect on the properties of the resulting oxide. The method developed could be used to obtain tetragonal zirconia (without expensive reagents and water consumption) and utilize wood industry wastes.     

Synthesis and photophysical properties of porphyrins with fluorenyl pendant arms

Symmetrical-A₄-porphyrins bearing four fluorene donor moieties TOFP (5,10,15,20-tetra(4-(2 methyloxyfluorenyl)phenyl)porphyrin) as well as eight fluorene arms OOFP (5,10,15,20-octa(3,5-(2-methyloxyfluorenyl)phenyl)porphyrin) were synthesized and characterized. Preliminary photophysical properties are reported. In comparison to the reference tetraphenylporphyrin TPP, the luminescence properties are slightly improved. The fluorescence quantum yields of tetrafluorenylporphyrin TOFP (1) and octafluorenylporphyrin OOFP (2) are 0.10 and 0.13, respectively.     

Pyridyl-substituted porphyrins: II. Synthesis and basic properties of dipyridylporphyrins

5,15-Bis(pyridin-2-yl)-, 5,15-bis(pyridin-3-yl)-, and 5,15-bis(pyridin-4-yl)-substituted 3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphyrins were synthesized, and their acid-base properties in ethanol-sulfuric acid were studied by spectrophotometric titration. Concentration ranges for the existence of mono- and dicationic forms of 5,15-dipyridylporphyrins and the corresponding ionization constants were determined. The effect of pyridine fragments on the basic properties of alkyl-substituted porphyrins was discussed.     

Meso-substituted cationic porphyrins of biological interest. Photophysical and physicochemical properties in solution and bound to liposomes

A series of cationic porphyrins with 1-4 positive charges are studied: mono(N-methyl-4-pyridyl)triphenylporphine chloride [Mono], cis(N-methyl-4-pyridyl)diphenylporphine chloride [Cis], tri(N-methyl-4-pyridyl)monophenylporphine chloride [Tri] and tetra(N-methyl-4-pyridyl)porphine chloride [Tetra]. Their photophysical properties are measured in small unilamellar vesicles and compared with those in homogeneous solution. Liposomes of L-alpha-dimyristoyl-phosphatidylcholine (100 nm diameter) and L-alpha-dipalmitoyl-phosphatidylcholine (50 nm diameter) in phosphate-buffered saline (pH = 7.4) or D2O 0.15 M NaCl were used. The effect of the medium microheterogeinity is discussed. The triplet quantum yields in liposomes for all the porphyrins are about 0.7, similar to the value obtained for Tetra in aqueous media. The singlet molecular oxygen quantum yields for the hydrophilic compounds Tri and Tetra are greater than those of the hydrophobic ones, Mono and Cis. Also, association constants (KL) of the dyes to liposomes and their localization within the membranes are determined from fluorescence and fluorescence polarization measurements, respectively. KL values are in the range of 10(4)-10(5) M-1 for all the compounds, indicating that hydrophobic and coulombic interactions between porphyrins and liposomes are responsible for the dye association. Fluorescence polarization experiments indicate that Mono and Cis can penetrate into the lipidic phase, and that Tri and Tetra are located near the polar heads of the lipidic molecules.     

Synthesis and physicochemical and catalytic properties of apatite-type lanthanum silicates

Undoped and aluminum-doped lanthanum silicates with an apatite structure have been synthesized using mechanical activation, and their structure, microstructure, and catalytic properties in the oxidative coupling of methane have been investigated. The phase composition, structure, and microstructure of the silicates have been determined by X-ray diffraction, IR spectroscopy, X-ray photoelectron spectroscopy, low-temperature nitrogen adsorption, and scanning and transmission electron microscopy. The catalytic activity of silicates have been investigated in a catalytic flow reactor at 700–800°C, a CH₄: O₂ molar ratio of 3.8: 1 in the feed, and a residence time of 0.04 s. The catalytic properties of apatite-type lanthanum silicates can be tuned by varying the number of cationic vacancies and/or interstitial oxygen ions through isomorphic substitution of atoms with a smaller oxidation number for silicon in the apatite lattice.     

Synthesis and physicochemical properties of low-substituted cationic ethers of starch

The kinetics of the formation of cationic starch ethers under the action of 3-chloro-2-hydroxypropyltrimethylammonium chloride is studied in relation to the reactant molar ratio, temperature, and concentration of the starch suspension. Comparative data on how the content of the introduced catoinic groups depends on the origin of native starch are presented. The efficiency of starch cationization and the physicochemical properties of the synthesized samples are examined by chemical analysis, scanning electron microscopy, X-ray diffraction analysis, and thermal gravimetric analysis.     

Synthesis and physicochemical properties of new fluorescent derivatives of cytosine

Sixteen new fluorescent N⁴‐(E)‐stilbenyloxyalkylcarbonyl‐cytosines 9–16 and N⁴‐(E)‐stilbenyloxyalkylcarbonyl‐1‐methylcytosines 17–24 have been synthesized. The differences in ¹H and ¹³C NMR spectra in two solvents (DMSO and TFA) have been pointed out and discussed. Assignment of the signals in the spectra of the compounds 9–24 in NMR in DMSO‐d₆ solutions has been made the basis of the homonuclear (COSY) and heteronuclear (HETCOR) spectra. The effect of the substituent (Cl, Br, NO₂) on the stilbene moiety on the fluorescence spectrum of each compound has been discussed.     

Synthesis and physicochemical properties of the pectin complexes with Xymedon

Russian Chemical Bulletin - The formation of stable complexes of pectin polysaccharides with 1-(2-hydroxyethyl)-4,6- dimethyl-1,2-dihydropyrimidin-2-one (Xymedon drug) was shown by UV and IR...     

Mesoporous cobalt and manganese spinels: Synthesis and physicochemical properties

Binary spinels of Со and Мn are obtained by means of hard-template synthesis. Their structural and chemical characteristics are determined via N₂-BET, XRD, and TEM. Their catalytic activity is studied using methanol oxidation as the model reaction.     

Synthesis and physicochemical properties of copolymers of aniline and 3,4-ethylenedioxythiophene

Copolymers of various compositions have been synthesized via copolymerization of aniline with 3,4-ethylenedioxythiophene in the presence of a poly(4-styrenesulfonic acid) matrix, and a mechanism of copolymerization has been suggested. It has been shown that the synthesized copolymers are included in non-stoichiometric interpolyelectrolyte complexes with matrices stabilized by salt bonds and nonionic interactions. The copolymers of aniline and ethylenedioxythiophene possess electrical conductivity and can enter into redox and acid-base reactions.     

Synthesis of formyl-substituted porphyrins

Syntheses of 1, 4, 5, 8-tetramethyl-2-ethoxycarbonyl-6-formylporphyrin and 1, 4, 5, 8-tetramethyl-2, 3-diethoxycarbonyl-6-formylporphyrin from the copper complexes of 1, 4, 5, 8-tetramethyl-2-ethoxycarbonylporphyrin and 1, 4, 5, 8-tetramethyl-2, 3-diethoxycarbonylporphyrin are described.     

Synthesis and physicochemical properties of cis- and trans-oxolane-3,4-diol derivatives

Conclusions Physicochemical properties of oxolane-3,4-diols, their dinitrates, diacetates, and ditosylates have been determined; the standard enthalpies of combustion and formation have also been measured for the first two series of derivatives.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 874–878, April, 1985.