Solvation of decane and benzene in mixtures of 1-octanol and <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethylformamide

The heats of dissolution of decane and benzene in a model system of octanol-1 (OctOH) and N,N-dimethylformamide (DMF) at 308 K are measured using a variable temperature calorimeter equipped with an isothermal shell. Standard enthalpies are determined and standard heat capacities of dissolution in the temperature range of 298–318 K are calculated using data obtained in [1, 2]. The state of hydrocarbon molecules in a binary mixture is studied in terms of the enhanced coordination model (ECM). Benzene is shown to be preferentially solvated by DMF over the range of physiological temperatures. The solvation shell of decane is found to be strongly enriched with 1-octanol. It is obvious that although both hydrocarbons are nonpolar, the presence of the aromatic π-system in benzene leads to drastic differences in their solvation in a lipid–protein medium.     

Thermochemistry of ethyl acetate solvation in the 1-octanol-N,N-dimethylformamide system

The thermal effects of ethyl acetate (EtOAc), 1-octanol (OctOH), and N,N-dimethylformamide (DMF) solution in a OctOH-DMF model system were measured using a calorimeter of variable temperature with an isothermal shell at 298 K. The standard enthalpies of solution and ester transfer from an alcohol to a binary mixture, and partial mole enthalpies of mixed solvent components were determined. The state of non-electrolyte molecules in OctOH-DMF and OctOH-DMF-EtOAc systems were studied using extended coordination model. It was found that the binary solvent is subjected to microclusterization, since the fraction of the single-type molecules in the solvation sphere of both components of a mixture is significantly higher than in the liquid phase volume. The conclusion was drawn that in the triple system, the ethyl acetate solvation sphere in the whole range of compositions is significantly enriched with amide owing to stronger esteramide dipole-dipole interaction.     

Blood porphyrins in binary mixtures of N,N-dimethylformamide with 1-octanol and chloroform: The energetics of solvation, (solute + cosolvent) interactions and model calculations

This study provides the first accurate analysis of the energetics of solvation of blood porphyrins in binary solvents which are considered as appropriate models for a smooth transition from a polar protein-like phase to an apolar lipid-like environment. Our results do indicate that hematoporphyrin dimethylether dimethylester (HDEDE) and deuteroporphyrin dimethylether (DDE), as well as the model of their ester side-chains ethyl acetate (EtOAc), reveal more exothermic solvation in chloroform (CHCl₃) than in dimethylformamide (DMF) and, especially, in 1-octanol (OctOH). The energetics of pair interaction between dissolved species and cosolvent molecules both in a protein-like and a lipid-like environment are clearly associated with these solvation effects. The interaction between blood porphyrins and DMF in OctOH is accompanied by large negative enthalpy changes at both temperatures, whereas in chloroform, forming strong H-bonds with dissolved species, the interaction is strongly thermochemically repulsive. All solute molecules interact in the energetically unfavorable way with OctOH and CHCl₃ in DMF, the effect being much stronger pronounced for chloroform. The most significant result of this work is that it is possible to connect this pair interaction in a highly diluted solution with the solute behavior in the entire range of the binary mixture. The approach proposed is independent of a solute and solvent structure, it provides a good prediction of the energetics of solvation in mixed solvents and can be extended for a lot of other biologically active solutes.     

Enthalpies of mixing and intermolecular interactions in the 1-octanol-dimethylformamide system at 298–318 K

The heat effects of solution of N,N-dimethylformamide (DMF) and 1-octanol (OctOH) in the DMF (1)-OctOH (2) system are measured over the range of compositions using a variable-temperature isothermal-shell calorimeter at 298, 308, and 318 K. The partial molar enthalpies of the binary mixture components and the enthalpies and heat capacities of mixing are determined. It is found that the amide-alcohol mixing is strongly endothermic and very weakly depends on temperature. The enthalpy and specific heat parameters of binary and ternary interactions between the DMF molecules in OctOH and the OctOH molecules in DMF are determined in terms of the virial expansion technique, and it is shown that the two nonelectrolytes exhibit a tendency to homoassociation.     

Enthalpies and Heat Capacities of Ethyl Acetate Solutions in Water and in Several Organic Solvents at 298–318 K

The enthalpies of solution of ethylacetate (EtOAc) in water, octane and 1-octanol (OctOH) were measured at 298, 308 and 318 K using a precise isoperibol calorimeter. The standard enthalpies and heat capacities of these non-electrolyte solution were computed and compared with the previously obtained ??_sol H ^° and $\Delta C_{p}^{\circ}$ values in N,N-dimethylformamide (DMF). Partial molal heat capacities of EtOAc in water and in organic solvents were calculated and compared with the available literature values.     

Trans-effect in the kinetics of reactions of mixed Cu(II) acetate solvates with N-methyloctaethylporphine

The kinetics of complex formation reaction of N-substituted octaethylporphine (H(N-Me)(β-Et)₈P] with copper(II) acetate in individual and mixed solvents based on DMSO, DMF, and Py is studied by spectrophotometry. An increase in the complex formation rate of this porphyrin with CuAc₂ in mixed solvents is explained in terms of the trans-effect of the ligands in the solvate sphere of the salt.     

Molecular polarizability of organic compounds and their complexes: L. Molar volumes and steric structure of some schiff bases and their structural analogs in infinitely dilute solutions

Molar volumes of a wide series of Schiff bases and their structural analogs, such as N-benzyl-ideneaniline N-oxides and azo compounds, in infinitely dilute solutions were determined. Analysis of the obtained values in terms of the additivity scheme showed that molecular fragments and substituting groups in these compounds are strongly solvated by solvent molecules, which leads to deviation of most molecules from the planar arrangement of the aryl moieties and bridging groups. Most compounds in which H-chelate rings are formed due to intramolecular hydrogen bonding are characterized by contraction of molar volumes, indicating their entropy stabilization in solution via release of solvent molecules from the solvate shell upon chelation. Methods for the determination of dipole moments and Kerr constants in solution can be simplified to a considerable extent for those compounds for which the additivity scheme was applied to calculate the molar volumes.     

Alkali-ion microsolvation with benzene molecules

The target of this investigation is to characterize by a recently developed methodology, the main features of the first solvation shells of alkaline ions in nonpolar environments due to aromatic rings, which is of crucial relevance to understand the selectivity of several biochemical phenomena. We employ an evolutionary algorithm to obtain putative global minima of clusters formed with alkali-ions (M(+)) solvated with n benzene (Bz) molecules, i.e., M(+)-(Bz)(n). The global intermolecular interaction has been decomposed in Bz-Bz and in M(+)-Bz contributions, using a potential model based on different decompositions of the molecular polarizability of benzene. Specifically, we have studied the microsolvation of Na(+), K(+), and Cs(+) with benzene molecules. Microsolvation clusters up to n = 21 benzene molecules are involved in this work and the achieved global minimum structures are reported and discussed in detail. We observe that the number of benzene molecules allocated in the first solvation shell increases with the size of the cation, showing three molecules for Na(+) and four for both K(+) and Cs(+). The structure of this solvation shell keeps approximately unchanged as more benzene molecules are added to the cluster, which is independent of the ion. Particularly stable structures, so-called "magic numbers", arise for various nuclearities of the three alkali-ions. Strong "magic numbers" appear at n = 2, 3, and 4 for Na(+), K(+), and Cs(+), respectively. In addition, another set of weaker "magic numbers" (three per alkali-ion) are reported for larger nuclearities.     

Cationic polymerization of 1,3-pentadiene : IV. Initiation by aluminum chloride in an apolar solvent: effect of various electron donors

The polymerization of 1,3-pentadiene (PD) initiated by aluminum trichloride in nonpolar solvent was carried out in the presence of various electron donors (EDs) such as ethyl acetate, (EtOAc) tert-butyl acetate, dimethyl phthalate (DMP), N,N-dimethyl formamide, N,N-dimethyl acetamide and dimethyl sulfoxide. Addition of an ED whatever its nature to the polymerization medium, in a one-to-one molar ratio relatively to the Lewis acid, resulted in a decrease of the overall yield and an increased proportion of crosslinked polymer. The molecular weight distribution of the soluble fraction was narrower than that of polymerizations carried out without ED. The microstructure of the soluble polymers can be tuned using different EDs, showing that they are interacting with the active species. For instance EtOAc increased polymer isomerization while DMP increased polymer cyclization. Thus, the nature of the chemical functions borne by the ED does not seem to be the only parameter explaining its influence on the polyPD microstructure. If crosslinking efficiency seems to be roughly correlated to the donicity scale of the EDs, termination reaction is not. It was shown that the complexation between the Lewis acid and the EDs containing a carbonyl group involved the carbonyl oxygen atom. The decrease of polymerization yield when using the EDs was assigned to this complexation between the ED and AlCl₃.     

Synthesis and structure of tris(4-N,N-dimethylaminophenyl)antimony(V) difluoride, dichloride, and dibenzoate

tris(4-N,N-Dimethylaminophenyl)antimony dichloride (I) was prepared by the reaction of tris(4-N,N-dimethylaminophenyl)antimony with copper dichloride. tris(4-N,N-Dimethylaminophenyl)antimony difluoride benzene disolvate II was synthesized from dichloride I and sodium fluoride in aqueous acetone with the subsequent crystallization from benzene. tris(4-N,N-Dimethylaminophenyl)antimony dibenzoate III was obtained from tris(4-N,N-dimethylaminophenyl)antimony and benzoic acid in the presence of hydrogen peroxide in ether or from silver benzoate and the corresponding dichloride in acetone. According to X-ray studies Sb atoms in two crystallographically independent molecules of dichloride, difluoride benzene solvate, and dibenzoate have the distorted trigonal bipyramide coordination [ClSbCl, FSbF, and OSbO trans angles are 178.12(2)°, 178.57(3)°, 177.30°, and 176.49° respectively). Sb-Cl, Sb-F, and Sb-O interatomic distances are 2.4719(7)-2.505(7); 2.106(4); 2.438(2); 2.1212(13) Å respectively. The oxygen atoms of carbonyl groups of the molecule III (C _2v molecular symmetry) are coordinated to the central atom [Sb-O distance 2.987(1) Å].     

Clathrate solvates of tetra­kis(4‐methoxy­carbonyl­phenyl)porphyrin and its zinc(II)–pyridine complex,in which the porphyrin host structures are stabilized by porphyrin–porphyrin stacking and C—H⋯O attractions

Tetra­kis(4‐methoxy­carbonyl­phenyl)porphyrin, or tetra­methyl 4,4′,4′′,4′′′‐porphyrin‐5,10,15,20‐tetra­benzoate, crystallizes as a nitro­benzene 1.9‐solvate, C₅₂H₃₈N₄O₈·1.9C₆H₅NO₂, (I). The solvent mol­ecules are contained in extended channels which propagate through the host lattice between parallel screw/glide‐related columns of offset‐stacked porphyrin entities. Side packing of these columns involves π–π inter­actions between the methoxy­carbonyl­phenyl residues. Mol­ecules of the porphyrin host lie on crystallographic inversion centres. The zinc(II)–pyridine derivative pyridine­(tetra­methyl 4,4′,4′′,4′′′‐porphyrin‐5,10,15,20‐tetra­benzoato)zinc(II), [Zn(C₅₂H₃₆N₄O₈)(C₅H₅N)], (II), is a square‐pyramidal five‐coordinate complex with pyridine as an apical ligand, which crystallizes as a chloro­form–pyridine solvate. The metallo­porphyrin–pyridine units form an open layered arrangement, occluding the non‐coordinated solvent moieties within the intra­layer inter­porphyrin voids. Within such arrays, the host porphyrin mol­ecules are in contact with one another through the peripheral methoxy­carbonyl substituents. The crystal packing consists of a bilayered arrangement of inversion‐related porphyrin layers, with the axial ligands mutually penetrating into the voids of neighbouring arrays and tight offset stacking of these bilayers.     

Solvates with anomalous low melting points

Single crystals of the N,N-dimethylformamide (DMF) solvate (1:1) of flurbiprofen (FBP) were grown for the first time and characterised by X-ray diffraction, IR spectrophotometry, DSC and solution calorimetric methods. The structure may be characterised as a layer-structure, where DMF double-sheets are arranged between FBP double-sheets. The FBP and DMF molecules are linked to each other by a hydrogen bond, which is formed between the hydroxyl group of FBP and the carbonyl group of DMF. The conformation of FBP molecules in the DMF solvate differs from analogous enantiomers in the unsolvated form. The differences are discussed from the point of view of the influence of the nature of the solvent on selective crystallisation of the enantiomers. A peculiarity of the solvate is its low melting point, 37.3±0.2°C, with respect to the unsolvated phase, 113.5±0.2°C. Based on solution enthalpies of the solvated and unsolvated phases dissolved in DMF, the difference in crystal lattice energies, 9.8 kJ mol^-1, was calculated and the difference in entropies, 33 J mol^-1 K^-1 estimated. A possible mechanism explaining the low melting point of the solvate is discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

The effect of ligand basicity on the thermal stability of heterodinuclear NiII–ZnII complexes

Four complexes of the nuclear structure Ni^II–Zn^II were prepared with bis-N,N′-(salicylidene)-1,3-propanediamine (LH₂), bis-N,N′-(salicylidene)-2,2′-dimethyl-1,3-propanediamine (LDMH₂) and the reduced derivatives of these Schiff bases, bis-N,N′-(2-hydroxybenzyl)-1,3-propanediamine (L^HH₂), bis-N,N′-(2-hydroxybenzyl)-2,2′-dimethyl-1,3-propanediamine (LDM^HH₂). The complexes were characterized using IR spectroscopy, elemental analysis and thermogravimetric methods. The stoichiometry of the complex molecules were found to be NiL·ZnCl₂·(DMF)₂, NiLDM·ZnCl₂·(DMF)₂, NiL^H·ZnCl₂·(DMF)₂ and NiLDM^H·ZnCl₂·(DMF)₂. The molecular models of the complexes prepared with the reduced Schiff bases were determined according to the X-ray diffraction method. It is seen that in these complexes Ni(II) is in octahedral and Zn(II) is in tetrahedral coordination sphere. Ni(II) ion is coordinated between two nitrogen and two oxygen donors of the ligand and oxygen donors of the two DMF molecules. Zn(II) ion on the other hand is coordinated between two oxygen of the organic ligand forming two μ bonds. It also coordinates two Cl ions. The thermogravimetric analysis showed that the complex NiLDM^H·ZnCl₂·(DMF)₂ containing methyl groups is more stable than the other complex NiL^H·ZnCl₂·(DMF)₂ containing reduced Schiff base. The coordinative DMF molecules in NiLDM^H·ZnCl₂·(DMF)₂ were thermally cleaved. However, the cleavage of DMF molecules NiL^H·ZnCl₂·(DMF)₂ resulted in the thermal degradation of the complex. In order to explain the TG data of the ligands were titrated in non-aqueous medium and their basicity strengths were determined. It was found that the basicity of the ligands containing two methyl groups were stronger. It is understood that the two methyl groups increase the negative charge density on nitrogen causing an increase in complex stability.     

Ligand trans-effect in octahedral complexes of 3d metals and its manifestation in the synthesis of metalloporphyrins in solution

We study features of the indicator kinetic reaction of meso(tetraphenyl)tetrabenzoporhine with cobalt(II), nickel(II), and manganese(II) acetates in electron-donating organic solvents (N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and pyridine (Py)) and in their binary mixtures at temperatures in the range 348–368 K. Specific features of the trans-effect of solvent molecules on the rate and activation parameters of formation of manganese(II), cobalt(II), nickel(II), and copper(II) complexes with porphyrin are noted.     

Enthalpies of mixing and intermolecular interactions in N,N-dimethylformamide-chloroform systems at temperatures ranging between 288 and 308 K

The thermal effects of N,N-dimethylformamide (DMF) and chloroform (ChF) dissolution in the ChF-DMF system are calorimetrically determined at 288, 298, and 308 K over the range of compositions. The partial molar enthalpies of the components are also calculated, along with the values for the enthalpies of mixing. It is found that mixing is a strongly exothermic process and depends only slightly on temperature. The enthalpy parameters of double and triple interactions between DMF molecules in ChF, and between ChF molecules in DMF, are determined using virial expansions.     

卟啉敏化的钛酸盐纳米管的可见光催化活性

制备了四碘化5,10,15,20-四(对-N,N,N三甲基苯胺基)卟啉敏化的钛酸盐纳米管(TAPPI-TNTs),并利用甲基橙(MO)作为模型污染物考察了其可见光催化活性。结果表明,TAPPI-TNTs是一个高效的可见光催化剂,在其催化作用下,可见光照射1 h后,甲基橙的降解率为89%。与此相反,纯钛酸盐纳米管并不具有可见光催化活性。此外,TAPPI-TNTs的稳定性较高,可以多次循环使用,在第五次循环中,甲基橙的降解率仍可达到50%以上。这可能是由于带正电荷的卟啉与带负电荷的钛酸盐纳米管之间存在着较强的静电吸引作用,卟啉紧密地吸附在钛酸盐纳米管上,导致卟啉的光激发电子易于向钛酸盐纳米管转移,从而使钛酸盐纳米管得到了有效敏化。     

2,4‐Di­nitro­phenyl­hydrazones of 2,4‐di­hydroxy­benz­aldehyde, 2,4‐di­hydroxy­aceto­phenone and 2,4‐di­hydroxy­benzo­phenone

In 2,4‐di­hydroxy­benz­aldehyde 2,4‐di­nitro­phenyl­hydrazone N,N‐di­methyl­form­amide solvate {or 4‐[(2,4‐di­nitro­phenyl)­hydrazono­methyl]­benzene‐1,3‐diol N,N‐di­methyl­form­amide solvate}, C₁₃H₁₀N₄O₆·C₃H₇NO, (X), 2,4‐di­hydroxy­aceto­phenone 2,4‐di­nitro­phenyl­hydrazone N,N‐di­methyl­form­am­ide solvate (or 4‐{1‐[(2,4‐di­nitro­phenyl)hydrazono]ethyl}benzene‐1,3‐diol N,N‐di­methyl­form­amide solvate), C₁₄H₁₂N₄O₆·C₃H₇NO, (XI), and 2,4‐di­hydroxy­benzo­phenone 2,4‐di­nitro­phenyl­hydrazone N,N‐di­methyl­acet­amide solvate (or 4‐­{[(2,4‐di­nitro­phenyl)hydrazono]phenyl­methyl}benzene‐1,3‐diol N,N‐di­methyl­acet­amide solvate), C₁₉H₁₄N₄O₆·C₄H₉NO, (XII), the molecules all lack a center of symmetry, crystallize in centrosymmetric space groups and have been observed to exhibit non‐linear optical activity. In each case, the hydrazone skeleton is fairly planar, facilitated by the presence of two intramolecular hydrogen bonds and some partial N—N double‐bond character. Each molecule is hydrogen bonded to one solvent mol­ecule.     

Effect of Increasing Concentration of Each of Three Polar Solvents (1,4-Dioxane, Dimethyl Sulfoxide, N,N-Dimethylformamide) on Changes in the Shape of Polysorbate 20 Micelles

The effect of increasing concentration of each of three polar solvents [0–40 % (v/v) 1,4-dioxane, 0–40 % (v/v) dimethyl sulfoxide (DMSO), and 0–60 % (v/v) N,N-dimethylformamide (DMF)] on changes in the shape of the surfactant polysorbate 20 (Tween 20) micelles in the aqueous, polar solvent, sodium phosphate buffer solutions (pH = 7.2, ionic strength 2.44 mmol·L^?1) were investigated by using small-angle X-ray scattering. The effect of increasing concentration of 1,4-dioxane is that the micelle shape changed from core–shell cylindrical micelles to core–shell disc micelles between concentrations of 10 and 20 % (v/v) 1,4-dioxane, and then from core–shell disc micelles to core–shell elliptic disc micelles between concentrations of 30 and 40 % (v/v) 1,4-dioxane. The effect of increasing concentration of DMSO is that the micelles changed from core–shell cylindrical micelles to core–shell disc micelles between concentrations of 0 and 10 % (v/v) DMSO. The effect of increasing concentration of DMF is that it changed the core–shell cylindrical micelles to core–shell disc micelles between concentrations of 30 and 40 % (v/v) DMF. The common effect is that the solvents shortened the height of the micelle, that is, they squashed the micelle. Moreover, the specific effect of 1,4-dioxane is that this solvent squashed and squeezed the micelle.     

Supramolecular hydrogen bonding of [5,10,15,20‐tetrakis(4‐carboxyphenyl)porphyrinato]palladium(II) in the presence of competing solvents

The title porphyrin compound forms hydrogen‐bonded adducts with methanol (1:1), [Pd(C₄₈H₂₈N₄O₈)]·CH₄O, (I), and with water and N,N‐dimethylformamide (1:4:4), [Pd(C₄₈H₂₈N₄O₈)]·4C₃H₇NO·4H₂O, (II). In (I), the metalloporphyrin unit lies across a mirror plane in Cmca, while in (II), this unit lies across an inversion center in P. Extended supramolecular hydrogen‐bonded arrays are formed in (I) by intermolecular interactions between the carboxylic acid functions, either directly or through the methanol species. These layers have a wavy topology and large interporphyrin pores, which are filled in the crystal structure by double interpenetration as well as enclathration of additional non‐interacting nitrobenzene solvent molecules. The supramolecular aggregation in (II) can be characterized by cascaded porphyrin layers, wherein adjacent porphyrin molecules are hydrogen bonded to one another through molecules of water that are incorporated into the hydrogen‐bonding scheme. Molecules of dimethylformamide partly solvate the carboxylic acid groups and fill the interporphyrin space in the crystal structure.     

Crystal structure and magnetic properties of a thiocyanato-bridged dinuclear Cr(III)Cu(II) complex [(HL)Cu(SCN)Cr(NCS)3(NH3)2]·DMF

The complex [(HL)Cu(SCN)Cr(NCS)₃(NH₃)₂]·DMF [H₂L=3,3′-trimethylenedinitrilobis(2-butanoneoxime), DMF=N,N′-dimethylformamide] has been synthesized and the structure determined by single-crystal X-ray diffraction. The structure consists of a dinuclear thiocyanato-bridged Cr(III)Cu(II) unit and a DMF molecule as crystal solvate. The chromium ion is six-coordinated with two NH₃ molecules in axial positions and four nitrogen atoms, from four NCS⁻, in equatorial positions. One of the NCS⁻ bridges the Cr and Cu ions, the S atom of which occupies the apex of the square-pyramidal coordination at Cu with the tetradentate HL ligand in the basal site. Cryomagnetic measurement revealed a weak antiferromagnetic coupling between the heterometal ions with J=−0.63 cm⁻¹ based on the spin Hamiltonian H=−2JS₁S₂.