Generation of Nanostructures by the Aggregation of Porphyrin Derivatives with Long Alkane Chain in Mix-Solvent

Controlled aggregation of tetrakis-(4-(hexadecyl oxy)-phenyl) porphyrin and its copper(II)-complex was studied in mix-solvent system at room temperature. Structure of the aggregates was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and UV-visible spectroscopy. TEM results indicated the formation of organized nanostructures from the porphyrin derivative and its corresponding copper(II)-complex. XRD results showed that the bulk and nanostructured free porphyrin derivatives had the similar crystalline morphology. UV-visible-NIR spectroscopic data showed broad red-shifted Soret band, indicating JJ aggregation among the monomer units. Conjugate effect of lateral π-π interaction among the tetrapyrrole cores and hydrophobic interaction among the long alkane chains substituted in the peripheral phenyl rings is believed to lead to the organized nanostructures. Effect of solvent ratio on the aggregate structure is also revealed

Positive and negative allosteric effects of thiacalix[4]arene-based receptors having urea and crown-ether moieties

Heteroditopic receptors (4ₐ₋ₑ) based on a thiacalix[4]arene in the 1,3-alternate conformation, which have two urea moieties linking various phenyl groups substituted with either electron-donating or -withdrawing groups at their m-, or p-positions with a crown-ether moiety at the opposite side of the thiacalix[4]arene cavity, have been synthesized. The two examples with p-CH₃– (4b) and p-NO₂-substituted (4ₑ) phenyl groups have been characterized by X-ray crystallography. The binding properties of receptor 4ₑ were investigated by means of ¹H NMR spectroscopic and absorption titration experiments in CHCl₃–DMSO (10:1, v/v) solution in the presence of K⁺ ions and various anions. Interestingly, it was found that receptor 4ₑ, which possesses two p-nitrophenyl ureido moieties, can complex most efficiently in the urea cavity or the crown-ether moiety; and the plausible allosteric effect of receptor 4ₑ was also studied

[2,2'-Bipyridyl]-3,3'-diol as a molecular half-subtractor

Spectral responses at two different wavelengths revealed that BP(OH)<SUB>2</SUB> ([2,2'-bipyridyl]-3,3'-diol) can function as a combinatorial logic circuit for a molecular half-subtractor with acid and base as input variables

Vesicles Functionalized with a CO-Releasing Molecule for Light-Induced CO Delivery

In this paper, a new type of methodology to deliver carbon monoxide (CO) for biological applications has been introduced. An amphiphilic manganese carbonyl complex (<b>1.Mn</b>) incorporated into the 1,2-distearoyl-sn-glycero-3-phosphocholine lipid vesicles has been reported first time for the photoinduced release of CO. The liposomes (<b>Ves-1.Mn</b>) gradually released CO under light at 365 nm over a period of 50 min with a half-time of 26.5 min. The CO-releasing ability of vesicles appended with <b>1.Mn</b> complexes has been confirmed by myoglobin assay and infrared study. The vesicles appended with <b>1.Mn</b> have the advantages of biocompatibility, water solubility, and steady and slow CO release. This approach could be a rational approach for applying various water-insoluble photoinduced CO donors in aqueous media by using vesicles as a nanocarrier for CO release

A density functional study towards substituent effects on anion sensing with urea receptors

Effects of substituents on anion binding in different urea based receptors have been examined using density functional (B3LYP/6-311+G**) level of theory. The complexes formed by a variety of substituted urea with a halide anion (fluoride) and an oxy-anion (acetate) have been calculated. The stronger complexes were predicted for receptors with fluoride ion than that of acetate ion, however, in water the preference was found to be reversed. The pKa calculations showed the preferred sites of deprotonation for positional isomers, while interacting with anions. The position of the substituent in the receptor, however, could change the preferred sites of deprotonation compared to the site predicted with pKa values

Rugby-ball-shaped sulfate-water-sulfate adduct encapsulated in a neutral molecular receptor capsule

We report a tren-based tris(urea) receptor molecule that shows preferential binding with sulfate/phosphate anions. The receptor acts as a neutral molecular capsule, within which a unique sulfate-(H2O)3-sulfate adduct is encapsulated

Efficient and simple colorimetric fluoride ion sensor based on receptors having urea and thiourea binding sites

Novel colorimetric receptors for selective fluoride ion sensing containing anthraquinone as chromogenic signaling subunit and urea (N,N"-(9,10-dihydro-9,10-dioxo-1,2-anthracenediyl)bis[N'-phenyl])/thiourea (N,N"-(9,10-dihydro-9,10-dihydro-9,10-dioxo-1,2-antrhacenediyl)bis[N-phenyl]) binding sites have been reported. These receptors have shown no affinity for other halide ions (Cl-, Br-, and I- ions). Well-defined color change in the visible region of the spectrum was observed upon addition of fluoride ion in DMSO/CH3CN solution of the receptors 1 and 2

From diamondoid network to (4, 4) net: effect of ligand topology on the supramolecular structural diversity

While N,N'-bis(4-pyridyl)urea affords a 5-fold interpenetrated diamondoid network, its positional isomer N,N'-bis(3-pyridyl)urea gave a net-to-net hydrogen-bonded (4,4) net (square grid network) displaying temperature-dependent anion-induced reversible single-crystal-to-single-crystal disorder-order phase transition, when the ligands are reacted with zinc perchlorate

Nonpolymeric hydrogelator derived from N-(4-Pyridyl)isonicotinamide

A series of pyridyl amides derived from isonicotinic acid, nicotinic acid, and benzoic acid have been synthesized. Only N-(4-pyridyl)isonicotinamide 1 is found to be an efficient hydrogelator with a minimum gelator concentration of 0.37 wt %. A wide range of concentrations (0.37-20 wt %) could be used to form hydrogels. The other amides, namely, N-(3-pyridyl)isonicotinamide 2, N-(2-pyridyl)isonicotinamide 3, N-(phenyl)isonicotinamide 4, N-(4-pyridyl)nicotinamide 5, N-(3-pyridyl)nicotinamide 6, and N-(4-pyridyl)benzamide 7, did not show any gelation properties. Fourier transform infrared spectroscopy, variable temperature 1H NMR, single-crystal diffraction and X-ray powder diffraction (XRPD), and scanning electron microscopy have been used to characterize the gel. Single-crystal diffraction and XRPD studies indicate that the morph responsible for gel formation is different from that in its bulk solid and xerogel