Surface-enhanced Raman study of the interactions between tripodal cationic polyamines and polynucleotides.

Raman and surface-enhanced Raman spectra of new DNA/RNA-binding compounds consisting of three imidazole (Im) and three pyridine (Py) rings connected by tripodal polyaminomethylene linkages were obtained by the near-infrared excitation at 1064 nm. Study of interactions of Im and Py polyamines with single-stranded RNA polynucleotides (poly A, poly G, poly C, poly U), double-stranded DNA polynucleotides (poly dAdT-poly dAdT, poly dGdC-poly dGdC) and calf thymus DNA (ct-DNA) by surface-enhanced Raman spectroscopy (SERS) reveals unambiguous enhancement of the Raman scattering from the small molecules as well as appearance of new bands in spectra associated mainly with nucleobases. The SERS experiments point toward comparable interactions of Im and Py polyamines with single-stranded purine and pyrimidine polynucleotides.

Surface-enhanced Raman spectra of rhodamine 19 octadecylamide.

Surface-enhanced Raman scattering (SERS) of the cationic and the neutral form of rhodamine 19 octadecylamide (R19OA) has been studied in the silver citrate colloid using NIR excitation at 1064 nm. Cationic molecules readily adsorb onto negatively charged silver nanoparticles through a positively charged xanthene part of the molecules resulting in surface enhancement of Raman scattering. Due to a lack of the positive charge in molecular structure, SERS spectrum of neutral molecules is not observed.

Surface-enhanced Raman scattering on molecular self-assembly in nanoparticle-hydrogel composite.

Surface-enhanced Raman scattering has been applied to study weak intermolecular interactions between small organic gelling molecules involved in the silver nanoparticle-hydrogel composite formation. Assembly and disassembly of the gelator molecules in close vicinity to embedded silver nanoparticles were followed by changes in Raman intensity of the amide II and carboxyl vibrational bands, whereas the strength of the bands related to benzene modes remained constant. This implied that the gelator molecules were strongly attached to the silver particles through the benzene units, while participating in gel structure organization by intermolecular hydrogen bonding between oxalyl amide and carboxyl groups.

Yb3+ as an origin of the strong anti-Stokes luminescence in NIR FT-Raman spectra of some lanthanide sesquioxides.

Strong anti-Stokes bands observed in FT-Raman spectra of Y2O3, Gd2O3 and Lu2O3 are explained by NIR luminescence of Yb3+ impurities present in sesquioxides after the excitation with the 1064 nm line of an Nd:YAG laser. Samples of Y2O3:Yb, Ga2O3:Yb, CeO2:Yb, Gd2O3:Yb and Lu2O3:Yb were prepared by solution combustion synthesis procedure using urea. All materials were investigated by FT-Raman and FT-NIR spectroscopy and characterized by X-ray powder diffraction.

Recognition of homo-polynucleotides containing adenine by a phenanthridinium bis-uracil conjugate in aqueous media.

Among novel bis-nucleobase-phenanthridinium conjugates bis-uracil analogue stabilized significantly more effective poly-dA-poly-dT and poly-AH(+)-poly-AH(+) than adenine analogue and reference compound . For the alternating poly-dAdT-poly-dAdT however, the binding preference is lost, pointing to the importance of specific interactions of uracils of with homopolynucleotides containing consecutive adenines.

Photoinduced gelation by stilbene oxalyl amide compounds.

Oxalyl amide derivatives bearing 4-dodecyloxy-stilbene as a cis-trans photoisomerizing unit were synthesized. The trans derivative acted as a versatile gelator of various organic solvents, whereas the corresponding cis derivative showed a poor gelation ability or none at all. In diluted solution (c = 2.