Catechin mediated one-step fabrication of ZnO microspheres: Synthesis, characterization and applications

A one-step template-free synthesis of hollow ZnO microspheres was developed by a hydrothermal route in presence of (+)-catechin as crystal habit modifier. Morphology evolution of ZnO particles showed the transformation from hexagonal rods to microspheres with increase in the concentration of catechin in the reaction medium. The microspheres were formed by the aggregation of fine grained nano-sized ZnO particles. The synthesized particles showed enhanced photocatalytic ability and high potency as a drug delivery agent

Catechin mediated one-step fabrication of ZnO microspheres: Synthesis, characterization and applications

1091-1099A one-step template-free synthesis of hollow ZnO microspheres has been developed by a hydrothermal route in the presence of (+)-catechin as crystal habit modifier. Morphology evolution of ZnO particles shows the transformation from hexagonal rods to microspheres with increase in the concentration of catechin in the reaction medium. The microspheres are formed by the aggregation of fine grained nano-sized ZnO particles. The synthesized particles show enhanced photocatalytic ability and high potency as a drug delivery agent

Differentiation of isomeric coordination geometries by metal valence: a structural study of its origin

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Synthesis, characterization and structure of the salicylate salt of [RuH(terpy)(PPh₃)₂]⁺(terpy = 2,2′ : 6′,2″-terpyridine)

The complex [RuH(terpy)(PPh₃)₂][C₇H₅O₃]1 has been synthesised from 2,2′ : 6′,2″-terpyridine (terpy) and [RuH(C₇H₅O₃)(PPh₃)₃] where C₇H₅O₃ is salicylate. It shows ν(RuH) at 1960 cm^–1 and a hydridic ¹H triplet at δ–6.30, J= 26.2 Hz. The crystal structure of 1 has been determined: space group Pnam, a= 14.705(7), b= 15.380(6), c= 22.667(9)Å, and Z= 4. The PPh₃ ligands are mutually trans about the Ru atom which, with the terpy ligand, lies on a mirror plane. The Ru–N distance trans to the hydride ligand is relatively long. The salicylate ion is internally hydrogen bonded. The complex displays a metal-to-ligand charge transfer transition (480 nm) and an irreversible metal oxidation Ru^II→Ru^III at ca. 0.6 V

Chemistry of a new family of carboxyl-chelated ruthenium and osmium aryls incorporating the imine-phenol motif

The reaction of carbonylhalo[4-methyl-6-(NR-iminiomethyl)phenolato-C<SUP>2</SUP>,O]bis(triphenylphosphine)metal(II), <SUP>II</SUP>(&#951;<SUP>2</SUP>-RL)(PPh<SUB>3</SUB>)<SUB>2</SUB>(CO)X (M = Ru, Os; X = Cl, Br; R = Ph, p-MeC<SUB>6</SUB>H<SUB>4</SUB>), 1, with sodium carboxylates has afforded carbonyl(carboxylato)[4-methyl-6-(NR-iminomethyl)phenol-C<SUP>2</SUP>]bis(triphenylphosphine)metal(II), M<SUP>II</SUP>(&#951;1-RL)(PPh<SUB>3</SUB>)<SUB>2</SUB>(CO)(&#951;<SUP>2</SUP>-R'CO<SUB>2</SUB>)(R' = Me, Ph), 2. The reaction is believed to proceed via initial associative cis attack on halide by carboxylate. The reaction 2&#8594; 1 occurs upon treatment of 2 with excess halide. Spectral (UV-vis, IR, <SUP>1</SUP>H NMR) and electrochemical (metal redox) data for 2 are reported. Structure determination of Ru(&#951;<SUP>1</SUP>-MeC<SUB>6</SUB>H<SUB>4</SUB>L)(PPh<SUB>3</SUB>)<SUB>2</SUB>(CO)(&#951;<SUP>2</SUP>-MeCO<SUB>2</SUB>) and Ru(&#951;<SUP>1</SUP>-MeC<SUB>6</SUB>H<SUB>4</SUB>L)(PPh<SUB>3</SUB>)<SUB>2</SUB>(CO)(&#951;<SUP>2</SUP>-PhCO<SUB>2</SUB>)·C<SUB>6</SUB>H<SUB>6</SUB> has revealed trans (PPh<SUB>3</SUB>)<SUB>2</SUB> geometry, the MeC<SUB>6</SUB>H<SUB>4</SUB>L ligand being bonded via an aromatic carbon atom lying cis to the CO molecule. In the H-bonded phenol-imine function the bond parameters for the acetate complex are as follows: O1-H, 1.14(3) &#197;; N···H, 1.52(3) &#197;; O1···N, 2.592(10) &#197;; O1-H···N, 156(1)&#176;. In the 1 &#8594; 2 interconversion, iminium-phenolate to imine-phenol tautomerization and a sterically controlled change in rotational conformation are involved

Photon harvesting in sunscreen-based functional nanoparticles

The ultraviolet light component in the solar spectrum is known to cause several harmful effects, such as allergy, skin ageing, and skin cancer. Thus, current research attention has been paid to the design and fundamental understanding of sunscreen-based materials. One of the most abundantly used sunscreen molecules is Avobenzone (AB), which exhibits two tautomers. Here, we highlight the preparation of spherically shaped nanoparticles from the sunscreen molecule AB as well as from sunscreen-molecule-encapsulated polymer nanoparticles in aqueous media and study their fundamental photophysical properties by steady-state and time-resolved spectroscopy. Steady-state studies confirm that the AB molecule is in the keto and enol forms in tetrahydrofuran, whereas the enol form is stable in the case of both AB nanoparticles and AB-encapsulated poly(methyl methacrylate) (PMMA) nanoparticles. Thus, the keto–enol transformation of AB molecules is restricted to a nanoenvironment. An enhancement of photostability in both the nanoparticle and PMMA-encapsulated forms under UV light irradiation is observed. The efficient excited energy transfer (60 %) from AB to porphyrin molecules opens up further prospects in potential applications as light-harvesting systems

Stable cyclohexadienyl complexes of ruthenium in a piano stool geometry containing a tridentate nitrogen donor ligand. First structural characterization of the (&#951;<SUP>5</SUP>-cyanocyclohexadienyl)ruthenium(ii) complex and spectroelectrochemical correlation

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