Theoretical models of the conformational behavior of flexible polymer chains in mixed solvents enunciated in the world literature during the last decade are critically reviewed. Models describing different mechanisms of coil-to-globule transitions in a good solvent induced by cosolvent addition are highlighted. Special attention is given to the analysis of theoretical approaches to describing the collapse of polymer chains in binary mixtures of good solvents. The review addresses researchers engaged in polymer physics and chemistry and materials scientists involved in the design of smart polymers.  

We present the simple microprobe for the investigation of crude oil by a thermal desorption photoionization coupled to Orbitrap mass spectrometry. The droplet of crude oil was placed on the heating element with controllable temperature. The temperature was linearly increased, and crude oil vapors were ionized by a vacuum ultraviolet (VUV) lamp and detected by Orbitrap mass spectrometer. Use of modified Orbitrap allowed introduction of the heating element and VUV lamp directly into the ion funnel and performing experiment not only at atmosphere pressure but also at 20, 10, and 5 torr. We observed that at high pressure protonated CHN compounds dominate in the spectrum, while at the low pressure CH compounds dominate. Similar to previously reported thermogravimetry coupled to photoionization or chemical ionization mass spectrometry systems we were able to separate compounds with different desorption energy and reliably detect low-abundant compounds. Also, we were able to determine the desorption temperature for each compound of the crude oil. We found that temperature of desorption increases linearly with m/z for compounds that belong to the same homology series (same Kendrick mass defect). This may serve as indirect evidence that such compounds differ only by the length of aliphatic chains attached to some basic structure.

The first synthesized and X-ray structurally characterized ‘‘classical’’ iron(I) dioximate showed an unrivaled stability towards strong acids, thus calling for a reassessment of the origins of the electrocatalytic activity of similar low-valent cobalt and iron cage complexes with electron-withdrawing ribbed substituents, shown previously to be effective electrocatalysts of the HER

A new approach to design “antenna-ligands” to enhance the photoluminescence of lanthanide coordination compounds based on π-type ligand - polyphenylsubstituted cyclopentadienyl has been developed. The complexes of di-, tri- and tetraphenyl cyclopentadienyl ligands with Tb and Gd has been synthesized and all the possible structural types from mononuclear to di- and tetranuclear as well as coordination polymer were obtained. All types of the complexes have been studied by single-crystal X-ray diffraction and optical spectroscopy. All complexes are luminescent at ambient temperature and two of them have relatively high quantum yields (50 and 60%). Analysis of energy transfer process has been performed and supported by quantum chemical calculations. The role of a low-lying intraligand charge transfer state formed by extra coordination with K+ in the Tb+3 ion luminescence sensitization is discussed. New aspects for design of lanthanide complexes containing π-type ligands with desired luminescence properties have been proposed.

A simple and effective synthetic route to homo- and heteroleptic rare-earth (Ln = Y, La and Nd) complexes with a tridentate Schiff base anion has been demonstrated using exchange reactions of rare-earth chlorides with in-situgenerated sodium (E)-2-{[(2-methoxyphenyl)imino]methyl}phenoxide in different molar ratios in absolute methanol. Five crystal structures have been determined and studied, namely tris(2-{[(2-methoxyphenyl)imino]methyl}- phenolato-3O1,N,O2)lanthanum, [La(C14H12NO2)3], (1), tris(2-{[(2-methoxyphenyl) imino]methyl}phenolato-3O1,N,O2)neodymium tetrahydrofuran disolvate, [La(C14H12NO2)3]2C4H8O, (2)2THF, tris(2-{[(2-methoxyphenyl)imino]- methyl}phenolato)-3O1,N,O2;3O1,N,O2;2N,O1-yttrium, [Y(C14H12NO2)3], (3), dichlorido-1Cl,2Cl--methanolato-1:22O:O-methanol-2O-(-2-{[(2-methoxyphenyl) imino]methyl}phenolato-13O1,N,O2:2O1)bis(2-{[(2-methoxyphenyl)- imino]methyl}phenolato)-13O1,N,O2;23O1,N,O2-diyttrium–tetrahydrofuran– methanol (1/1/1), [Y2(C14H12NO2)3(CH3O)Cl2(CH4O)]CH4OC4H8O, (4)- MeOHTHF, and bis(-2-{[(2-methoxyphenyl)imino]methyl}phenolato- 13O1,N,O2:2O1)bis(2-{[(2-methoxyphenyl)imino]methyl}phenolato-23O1,N,O2)- sodiumyttrium chloroform disolvate, [NaY(C14H12NO2)4]2CHCl3, (5)2CHCl3. Structural peculiarities of homoleptic tris(iminophenoxide)s (1)–(3), binuclear tris(iminophenoxide) (4) and homoleptic ate tetrakis(iminophenoxide) (5) are discussed. The nonflat Schiff base ligand displays 2-3O1,N,O2:O1 bridging, and 3O1,N,O2 and 2N,O1 terminal coordination modes, depending on steric congestion, which in turn depends on the ionic radii of the rare-earth metals and the number of coordinated ligands. It has been demonstrated that interligand dihedral angles of the phenoxide ligand are convenient for comparing steric hindrance in complexes. (4)MeOH has a flat Y2O2 rhomboid core and exhibits both inter- and intramolecular MeO—H  Cl hydrogen bonding. Catalytic systems based on complexes (1)–(3) and (5) have demonstrated medium catalytic performance in acrylonitrile polymerization, providing polyacrylonitrile samples with narrow polydispersity.

Four hybrid 3,3'-(alkane-1,n-di-yl)-bis(1-methyl-1H-imidazole-3-ium) halobismuthates were prepared by a facile solution route and characterized by diffuse reflectance spectra and photoluminescence measurements. Crystal structure of 3,3'-(buthane-1,4-di-yl)-bis(1-methyl-1H-imidazole-3-ium) bromo-bismuthate (1) contains zero-dimensional Bi2Br10 anions. Crystal structure of 3,3'-(pentane-1,5-di-yl)bis-(1-methyl-IH-imidazole-3-ium) iodobismuthate (4) contains zero-dimensional Bi2I9 anions.

The following bromobismuthates of organic cations (dipyridinoalkane derivatives) are synthesized and characterized: (4-NH2PyC5)BiBr5 (I), (2-MePyC2)BiBr5 (II), (2-NH2PyC10)BiBr5 center dot 0.65H(2)O (III), (2-NH2PyC10)(4)H5O2(BiBr6)(3) (IV), (2-NH2PyD6)(2)KBi2Br11 (V), (2-NH2PyC6)H3OBiBr6 center dot 2.33H(2)O (VI), and (2-NH2PyC6)(3)(BiBr6)(2) center dot CH3CN (VII). Three compounds obtained (I-III) contain the zigzag 1D chain (BiBr5) (n) . A new type of 1D chains, (KBi2Br11) (n) , is found in the structure of compound V. Pseudo-1D chains of BiBr6 (3-) anions can be observed in the 3D structures of compounds IV, VI, and VII. The crystallographic data were deposited with the Cambridge Crystallographic Data Centre (CIF files CCDC 1569478 (I)-1569484 (VII), respectively)

The relationship between crystal structures of three isomeric aminopyridinium iodobismuthates containing one-dimensional [(BiI4)n]n− anions, acidity of aminopyridinium cations and optical properties was revealed

The interaction of iodobismuthate anions and methyl viologen [MV]2+ cations in aqueous solutions led to the formation of three compounds, two of which were identified as [MV][BiI5] and [MV]3[Bi2I11]I. Hybrid iodobismuthates [MV]3[Bi2I11]I and [MV]3[Bi2I9]2(DMF)3(H2O) were isolated from dimethylformamide (DMF). The heating of the latter material (up to 200 o C) resulted in a mixture of products, one of which was identified as [MV][BiI5]. A simple antisolvent precipitation method was proposed to create the [MV] [BiI5]/SiO2 composite material.