The application of FTIR spectroscopy to concentrated solutions of tetrolic acid shows, for the first time, a direct relationship between molecular self association in solution and H-bonded motifs in the subsequently crystallised solid phases.

Little is known concerning the precise molecular pathway that links fluid-phase molecules to those in nascent crystal nuclei. In this paper the process of molecular self-assembly has been studied in concentrated solutions using FTIR spectroscopy. Three carboxylic acids, benzoic, tetrolic, and mandelic acids, have been chosen on the basis of their differing crystal chemistries, as reflected in observed hydrogen-bonding motifs. Using the solid-state spectra as a means of unambiguous assignment of carboxyl and hydroxyl vibrations associated with hydrogen bonding, spectroscopic data are reported for solutions as a function of both composition and solvent. In the cases of benzoic acid and tetrolic acid, a link between the growth synthon and the structural synthon is apparent. Mandelic acid, on the other hand, provides a more complex case in which strong solvation effects are evident, leading to the conclusion that significant molecular rearrangement must occur within the developing crystal nuclei.

Quaternization of the nitrogen atom of 2-amino-4-chlorophenyl phenyl sulfide analogues of chlorpromazine improved inhibition approximately 40-fold (3',4'-dichlorobenzyl-[5-chloro-2-phenylsulfanyl-phenylamino)-propyl]-dimethylammonium chloride inhibited trypanothione reductase from Trypanosoma cruzi with a linear competitive Ki value of 1.7 +/- 0.2 microM). Molecular modelling explained docking orientations and energies by: (i) involvement of the Z-site hydrophobic pocket (roughly bounded by F396', P398', and L399'), (ii) ionic interactions for the cationic nitrogen with Glu-466' or -467'. A series of N-acyl-2-amino-4-chlorophenyl sulfides showed mixed inhibition (Ki, Ki' = 11.3-42.8 microM). The quaternized analogues of the 2-chlorophenyl phenyl sulfides had strong antitrypanosomal and antileishmanial activity in vitro against T. brucei rhodesiense STIB900, T. cruzi Tulahuan, and Leishmania donovani HU3. The N-acyl-2-amino-4-chlorophenyl sulfides were active against Plasmodium falciparum. The phenothiazine and diaryl sulfide quaternary compounds were also powerful antimalarials, providing a new structural framework for antimalarial design.

A starch-urea-based biodegradable coordination polymer modified by transition metal Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) was prepared by polycondensation of starch and urea. All the synthesized polymeric compounds were characterized by Fourier transform-infrared spectroscopy (FT-IR), 1H-NMR spectroscopy, 13C-NMR spectroscopy, UV-visible spectra, magnetic moment measurements, differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA). The results of electronic spectra and magnetic moment measurements indicate that Mn(II), Co(II), and Ni(II) complexes show octahedral geometry, while Cu(II) and Zn(II) complexes show square planar and tetrahedral geometry, respectively. The thermogravimetric analysis revealed that all the polymeric metal complexes are more thermally stable than the parental ligand. In addition, biodegradable studies of all the polymeric compounds were also carried out through ASTM standards of biodegradable polymers by CO2 evolution method.

A new polymeric Schiff base containing formaldehyde and 2-thiobarbituric acid moieties was synthesized by the condensation of a monomeric Schiff base derived from 2-hydroxyacetophenone and hydrazine. Polymer-metal complexes were also synthesized by the reaction of the polymeric Schiff base with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) acetate. The polymeric Schiff base and its polymer-metal complexes were characterized with magnetic moment measurements, elemental analyses, and spectral techniques (infrared, 1 H-NMR, and ultraviolet-visible). The thermal behaviors of these coordination polymers were studied by thermogravimetric analysis in a nitrogen atmosphere up to 800 C. The thermal data revealed that all of the polymer-metal complexes showed higher thermal stabilities than the polymeric Schiff base and also ascribed that the Cu(II) polymer-metal complex showed better heat resistant properties than the other polymer-metal complexes. The antimicrobial activity was screened with the agar well diffusion method against various selected microorganisms, and all of the polymer-metal complexes showed good antimicrobial activity. Among all of the complexes, the antimicrobial activity of the Cu(II) polymer-metal complex showed the highest zone of inhibition because of its higher stability constant and may be used in biomedical applications.

A new polyester, poly-(ethylene oxamide-N,N -diacetate) (PEODA), containing glycine moiety was synthesized by the reaction of oxamide-N,N -diacetic acid and ethylene glycol and its polymer-metal complexes were synthesized with transition metal ions. The monomer oxamide-N,N -diacetic acid was prepared by the reaction of glycine and diethyl oxalate. The polymer and its metal complexes were characterized by elemental analysis and other spectroscopic techniques. The in vitro antibacterial activities of all the synthesized polymers were investigated against some bacteria and fungi. The analytical data revealed that the coordination polymers of Mn(II), Co(II) and Ni(II) are coordinated with two water molecules, which are further supported by FTIR spectra and TGA data. The polymer-metal complexes showed excellent antibacterial activities against both types of microorganisms; the polymeric ligand was also found to be effective but less so than the polymer-metal complexes. On the basis of the antimicrobial behavior, these polymers may be used as antifungal and antifouling coating materials in fields like life-saving medical devices and the bottoms of ships.

Aniline‐formaldehyde resin modified by adding piperazine (AFP) was prepared in alkaline medium, and its metal polychelates have also been prepared with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) metal ions. The synthesized compounds were characterized by elemental, spectral (UV–Vis, IR, 1H‐NMR and 13C‐NMR), thermogravimetric analysis (TGA), and magnetic moment measurements. The percentage of metal in all of the polychelates was found to be consistent with 1:1 (metal/resin) stoichiometry. The thermal behaviors of these coordination polymers were studied by TGA in a nitrogen atmosphere up to 750°C. The TGA results revealed that all the metal polychelates had higher thermal‐resistance property compared to the common resin (AFP). The magnetic moment measurements and UV–Vis spectra confirmed the geometry of the central metal ion in all the polychelates. All the synthesized metal polychelates showed excellent antibacterial activities against the selected bacteria. The antibacterial activities were determined using the shaking flask method, where 25 mg/ml concentrations of each compound were tested against 105 CFU/ml bacteria solutions. The number of viable bacteria was calculated by using the spread plate method, where 100 µl of the incubated antibacterial agent in bacteria solutions was spread on agar plates, and the number of bacteria was counted after 24 hr of incubation period at 37°C. Copyright © 2008 John Wiley & Sons, Ltd.

New polymeric ligand (resin) was prepared by the condensation of thiosemicarbazides with formaldehyde in the presence of acidic medium. Thisemicarbazide-formaldehyde polymer-metal complexes were prepared with Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) in 1 : 2 metal : ligand molar ratio. The polymeric ligand and its polymer-metal complexes were characterized by elemental analysis, thermogravimetric analysis (TGA), FTIR, 13 C NMR and 1 H NMR. The geometry of central metal ions was conformed by electronic (UV-vis) and EPR spectra. The antibacterial activities of all the synthesized polymers were investigated against Bacillus subtilis and Staphylococcus aureus (Gram-positive) and Escherichia coli and Salmonella typhi (Gram-negative). These compounds showed excellent activities against these bacteria using the shaking flask method.