Polytopic cation receptor functional phthalocyanines: Synthesis,characterization, electrochemistry and metal ion binding

Our efforts toward the development of the synthesis of a novel type of receptor ligand and its tetrasubstituted phthalocyanines, 2,9,16,23-tetrakis(6-hydroxyhexylsulfanyl) phthalocyanine, M[Pc(S–C₆H₁₃OH)₄] (M = Zn(II), Cu(II), Co(II)), bearing sulfur and oxygen donor atoms on the periphery together with hexyl moieties, have been carried out together with spectroscopic and electrochemical characterization. The newly synthesized functional phthalocyanines were soluble in MeOH, EtOH, THF, DMF, CNP (α-chloronapthalene), DMSO and quinoline, and less soluble in i-PrOH and CH₃CN. Cation binding abilities of the functional phthalocyanines with Ag⁺, Pd²⁺, Hg²⁺ and Cd²⁺, resulting in the formation of polynuclear phthalocyanine complexes, were evaluated by UV–Vis spectroscopic techniques. The spectroscopic properties of the complexes were affected strongly by the electron-donating sulfanyl units on the periphery. The cyclic voltammetry of the complexes were examined on a platinum electrode in DMSO. The new synthesized compounds have been characterized by elemental analysis, FTIR, ¹H and ¹³C NMR, MS (ESI and MALDI-TOF) and UV–Vis spectral data.     

Metal Complexes of Ditopic and Polytopic Macrocyclic Ligands

Soft Supramolecular Materials (SSM) are multicomponent materials formed bythe bulk supramolecular assembly/aggregation of building units into a regularstructure, with stronger bonding within building units and weaker bondingbetween them. The nature of the building units may vary from simple moleculesto nanoparticles, and the forces linking the units together may vary from coordinativeto van der Waals. Recently SSM have attracted a great deal of attention due to theirwide variability, easy conversion from one structure to another, and active responseto external stimuli. It seems evident that the progress in the chemistry of SSMpredestines the appearance of a new generation of functional and ``smart'' materials.     

Polymer-Bromine Interactions. I. Interactions with Polyacrylonitrile

The present paper deals with the interactions of bromine with poly-acrylonitrile (PAN). Kinetics and equilibria of the sorption of Br₂ on PAN were studied at a concentration range of 0.01–0.1 mol/L and a temperature range of 25–40°C. Two kinds of sorption were found: a “reversible” sorption removable by water and an “irreversible” sorption removable by aqueous ammonia solutions. The irreversibly sorbed bromine is presumably linked by charge transfer to the nitrile groups of the PAN, as evidenced by UV spectra. The irreversible sorption follows the reversible sorption and is slower. Partition coefficients obtained from the linear Freundlich isotherms increased with temperature and, at 40°C, the values obtained were 97, 65, and 32 L/kg for the total, irreversible, and reversible sorptions, respectively. At 25°C the chemical potential, enthalpy, and change in entropy for the irreversible sorption were ?2.0 kcal/mol, 9.4 kcal/mol, and 38 cal·mol^?1·K^?1. Effects of a 6-day Br₂ treatment and ammonia rinse were: decrease in dry T _g from 74.5 to 61°C and in water from 38 to 35°C; no significant decrease in M _W ; decrease in tensile strength measured after the bromine stage, and improvement after ammonia stage; increased swollen dimensions from 57% in water to 75%; and stabilization of swollen dimensions upon drying. The results support the existence of two phases in the less ordered regions of PAN.     

Specific Interactions. Intermolecular Forces,Steric Requirements,and Molecular Size

Specific interactions or recognition processes are extremely important in many fields of chemistry and biology: typical examples are the enzyme-substrate and the antigen-antibody reactions. Quantitative predictions require a knowledge of steric fit, intermolecular forces, and molecular size. These considerations should facilitate design of new drugs.     

DNA‐Surfactant Interactions. Compaction,Condensation, Decompaction and Phase Separation

Recent investigations of the interaction between DNA and alkyltrimethylammonium bromides of various chain lengths are reviewed. Several techniques have been used such as phase map determinations, fluorescence microscopy, and electron microscopy. Dissociation of the DNA‐surfactant complexes, by the addition of anionic surfactant, has received special attention. Precipitation maps for DNA‐cationic surfactant systems were evaluated by turbidimetry for different salt concentrations, temperatures and surfactant chain lengths. Single‐stranded DNA molecules precipitate at lower surfactant concentrations than double‐helix ones. It was also observed that these systems precipitate for very low concentrations of both DNA and surfactant, and that the extension of the two‐phase region increases for longer chain surfactants; these observations correlate well with fluorescence microscopy results, monitoring the system at a single molecule level. Dissociation of the DNA‐cationic surfactant complexes and a concomitant release of DNA was achieved by addition of anionic surfactants. The unfolding of DNA molecules, previously compacted with cationic surfactant, was shown to be strongly dependent on the anionic surfactant chain length; lower amounts of a longer chain surfactant were needed to release DNA into solution. On the other hand, no dependence on the hydrophobicity of the compacting agent was observed. The structures of the aggregates formed by the two surfactants, after the interaction with DNA, were imaged by cryogenic transmission electron microscopy. It is possible to predict the structure of the aggregates formed by the surfactants, like vesicles, from the phase behaviour of the mixed surfactant systems. The compaction of a medium size polyanion with shorter polycations was furthermore studied by means of Monte Carlo simulations. The polyanion chain suffers a sudden collapse as a function of the condensing agent concentration and of the number of charges on the molecules. Further increase of the concentration gives an increase of the degree of compaction. The compaction was found to be associated with the polycations promoting bridging between different sites of the polyanion. When the total charge of the polycations was lower than that of the polyanion, a significant translational motion of the compacting agent along the polyanion was observed, producing only a small‐degree of intrachain segregation. However, complete charge neutralization was not a prerequisite to achieve compacted forms.     

Tuning the Functional Properties of Metal Complexes Containing Polytopic Heteroaromatic Nitrogen Ligands

The preparation, characterization, and optimization of the functional properties of mono‐ and polynuclear coordination complexes containing heteroaromatic nitrogen ligands are discussed here, taking the advantage of numerous studies performed in our laboratories on exploring a variety of different metal ions and polytopic ligands. We highlight how very minor changes in connectivity, composition, and polarity of the molecular entities employed in the self‐assembly steps may significantly affect the structural, thermal, sorptive, magnetic, and mesomorphic behavior of the resulting materials. Examples from three different classes are included: 1) pyrazolate‐based polynuclear coordination compounds, 2) homoleptic and heteroleptic coordination polymers, and 3) 2,2′‐bipyridine metal‐based liquid crystals.     

Intramolecular Interactions in Anisole,Thioanisole, and Selenoanisole. Application of Natural Bond Orbitals Method

Calculations of molecules PhXMe (X = O, S, Se) in MP2(f)/6-31G(d) approximation were performed. The stationary points on the potential energy surface were determined and identified. The anisole molecule is planar with a barrier to rotation H 7.78 kJ mol^-1. In thioanisole and selenoanisole (H 3.08 and 10.25 kJ mol^-1 respectively) the energy minimum corresponds to an orthogonal form. Analysis of relation between intramolecular interactions and conformational structure of the molecules in question was performed by the method of natural bond orbitals. In X atoms one lone electron pair is a hybrid orbital with the following fraction of s-component: 38-45% (O), 66-68% (S), and 73-74% (Se). The second lone electron pair is virtually pure pz-AO.     

Interactions between collagen chains and fiber formation.

The temperature-dependent dissociation of neutral salt-soluble collagen into its component chains was measured in 0.6-1.6 M urea solutions at pH 7.3. The temperature-dependent association of the same radioactively labeled collagen into fibers was measured in 0-0.4 M urea solutions, pH 7.3. The effect of urea on the temperature, Tm(G), for half dissociation into chains was small, and the value extrapolated to zero urea concentration was 39 degrees C. In contrast, the effect of urea on the temperature, Tm(F), for half association into fibers was large, and the value at zero urea concentration was 30 degrees C. We conclude that while body temperature provides excellent conditions for the matching of collagen chains to form molecules, the conditions are not optimal for the formation of highly ordered fibers. The large effects of 0.1 M urea suggest that other factors in vivo may help to destabilize mismatched molecular association during fiber growth. Alternately this might be facilitated by parts of the extension peptides of procollagen.     

Interactions of thiophenes and acidophilic,thermophilic bacteria

The growth and oxygen consumption of a variety of thermophilic, acidophilic bacteria in the presence of thiophene-2-carboxylate (T2C) and dibenzothiophene (DBT) have been determined. T2C was extremely toxic to the acidophiles in comparison with neutrophiles, but appeared to be degraded by a heterotrophicSulfolobus- like thermophile. DBT proved to be unstable at high temperatures, even in the absence of bacteria, and was not a substrate for the thermophiles.     

Interactions between frenkel excitons. I. Formalism and preliminary results

For the tightest-bound Frenkel excitons a many-particle hamiltonian is adopted which includes terms representing interactions between the excitons. The parameters of the model are the excitation energy of an isolated localized excitation, the excitation-transfer matrix elements, and the interaction energies. Several special cases, involving particular relations between the latter two sets of parameters, are treated qualitatively. Equations are translated into the language of spin-$\text{1}\text{2}$ lattices, so that use may be made of the results of that theory. Favorable conditions for observation of polyexcitons and of phase transition to a liquid of excitons are discussed. A standard formalism for the determination of absorption and emission spectra and of their moments is adapted to the present problem. Possible generalizations of the model are briefly discussed.     

ChemInform Abstract: Electronic Structure and Energies of Interatomic Interactions in Technetium,Rhenium, Ruthenium,and Osmium Diborides.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

IR Spectra, Polymorphism, and Intermolecular Interactions in Carboxylic Acids

This paper summarizes the results of our studies on the structural aspects of polymorphism and mesomorphous states in long-chain aliphatic compounds represented by the homologous series of alkyl-, alkoxybenzoic, and alkylcyclohexanecarboxylic acids and their completely or partially fluorinated analogs. The studies were carried out by vibrational IR spectroscopy (experiment, theory), calorimetry, polarization microscopy, and X-ray diffractometry. Conformational polymorphs have been found for the compounds, which differ in the bending of alkyl and fluoroalkyl radicals and in rotation of carboxyl groups and phenyl rings during phase transitions. Structural rearrangements and dynamic changes take place inside the nuclei of H-complexes. The dimers are partially dissociated, and open associates, chain associates, and monomers differing in their conformational composition are formed.     

Colloidal behavior of nanoemulsions: Interactions,structure, and rheology

Nanoemulsions exhibit unique behavior due to their nanoscopic dimensions, including remarkable droplet stability, interactions, and rheology. These properties are significantly enhanced by nanoscopic droplet size, as well as the selection of surfactant and other molecular species in solution. Electrostatic and polymer-induced interdroplet interactions are particularly powerful tools for fine-tuning the interdroplet interactions, and have led to stimuli-responsive nanoemulsion systems that provide deep insight into their unique properties. As such, nanoemulsions have emerged as powerful model systems for studying a number of colloidal phenomena including suspension rheology, repulsive and attractive colloidal glasses, aggregation processes, colloidal gelation and phase instability, and associative network formation in polymer–colloid mixtures. This review summarizes recent advances in understanding the colloidal behavior of nanoemulsions, and provides a unifying framework for understanding the various complex states that emerge, as well as perspective on emerging challenges and opportunities that will advance the use of nanoemulsions in both fundamental colloid science and technological applications.     

Phosphorus-Nitrogen Compounds: Part 25. Syntheses,Spectroscopic, Structural and Electrochemical Investigations,Antimicrobial Activities,and DNA Interactions of Ferrocenyldiaminocyclotriphosphazenes

Abstract

The condensation reactions of hexachlorocyclotriphosphazene (N₃P₃Cl₆) with mono (1 and 2) and bisferrocenyldiamines (3–5 and 7) resulted in the formation of tetrachloro mono- (8 and 9) and bisferrocenylspirocyclotriphosphazenes (10–13). In addition the tetramorpholino mono- (8a and 9a) and bisferrocenylphosphazenes (10a–12a) were obtained from the reactions of the corresponding tetrachlorophosphazenes (8–12) with excess morpholine. The structures of all the phosphazenes were determined using FTIR, MS, ¹H, ¹³C, and ³¹P NMR and 2-dimensional NMR techniques. The structures of 9a and 13 were determined by single crystal X-ray diffraction techniques. Cyclic voltammetric investigations of compounds 8a, 9a, and 11a revealed that ferrocene redox centers undergo reversible oxidation. These ferrocenylphosphazenes appear to be quite robust electrochemically. Interactions between the compounds 8a, 9a, 11a, and 12a and pBR322 plasmid DNA were investigated by agarose gel electrophoresis.

[Supplementary materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional text and figures.]     

Reactions of perfluoronitriles. III. Interactions with diphenylphosphine

Reaction of perfluoro-n-octanonitrile with diphenylphosphine gave two products: a primary adduct, C₇F₁₅C(NH)P(C₆H₅)₂, and the reduced adduct, C₇F₁₅CH(NH₂)P(C₆H₅)₂. Presence of water prevented the formation of the reduced compound; the latter was not produced by reduction of the primary adduct. Operative mechanisms are postulated; infrared and mass spectra are discussed.     

Reactions of perfluoronitriles. II. Interactions with phenylphosphine

Treatment of perfluoro-n-octanonitrile with phenylphosphine gave tetraphenyltetraphosphine and a spectrum of reduction and interaction products. Fifteen compounds were identified. The imine, (R_fC₇F₁₅) R_fCHNH, and the amine, R_fCH₂NH₂, were the primary reduction products. Secondary phosphorus-free products, some formed following ammonia evolution, were the following: R_fCHNCH₂R_f, R_fCH₂CH(NH₂)R_f, R_fC(NH)NCR_f(NH₂), R_fCH₂NHCR_f(NH), (R_fCN)₃, R_fCHNCR_fNCR_f(NH), R_fCH₂NCR_fNHCH₂R_f, and R_fCH₂NCR_fNHCR_f(NH). Only three phosphorus-containing materials were definitely identified: R_fCH(NH₂)P(C₆H₅)H, R_fCH[P(C₆H₅)H]NCHR_f, and R_fC(NH)P(C₆H₅)CR_f(NH). Depending on reaction conditions, specific phosphorus-containing compounds could be preferentially produced. All the structure assignments are based solely on mass spectral breakdown patterns, since pure compounds were not isolated.     

Interactions between C.I. Basic Blue 41 and aluminosilicate sorbents

Four aluminosilicate sorbents (montmorillonite, bentonite, raw perlite, and expanded perlite) were employed for retention of the cationic dye C.I. Basic Blue 41. Interactions between the clay and the dyestuff were investigated at several temperatures and clay:dye ratios. The mechanism behind the adsorption involves the formation of H-aggregates of the dye on both clays, followed by dye migration into the interlayer in the case of montmorillonite. Time-dependent absorbance spectra revealed the presence of various dye species in montmorillonite. Introduction of the dye molecules into the interlamellar space occurs more rapidly in bentonite than in montmorillonite. The dye molecules inserted between the clay leaves adopt different orientations and, eventually, stack in layers at increased dye loadings for both montmorillonite and bentonite. Higher dye aggregates are then present as suggested by diffuse reflectance spectroscopy. Dye sorption on both raw and expanded perlite proceeds via H-aggregate formation as well.