Ai Ling Tan

Potential natural sensitizers extracted from the skin of Canarium odontophyllum fruits for dye-sensitized solar cells.

Possibility of use of dye extract from skin samples of a seasonal, indigenous fruit from Borneo, namely Canarium odontophyllum, in dye sensitized solar cells (DSSCs) are explored. Three main groups of flavonoid pigments are detected and these pigments exhibit different UV-vis absorption properties, and hence showing different light harvesting capabilities. When applied in DSSCs. The detected pigment constituents of the extract consist of aurone (maritimein), anthocyanidin (pelargonidin) and anthocyanidin (cyanidin derivatives). When tested in DSSC, the highest conversion efficiency of 1.43% is exhibited by cyanidin derivatives, and this is followed by conversion efficiencies of 0.51% and 0.79% for aurone and pelargonidin, respectively. It is shown that individual pigments, like cyanidin derivatives and pelargonidin, exhibit higher power conversion efficiency when compared to that of C.odontophyllum skin pigment mixture (with a conversion efficiency of only 0.68%). The results indicate a possibility of masking effects of the pigments when used as a mixture. The acidification of C.odontophyllum skin pigments with concentrated hydrochloric acid improves the conversion efficiency of the mixture from 0.68% to 0.99%. The discussion in this paper will draw data and observations from the variation in absorption and adsorption properties, the HOMO-LUMO levels, the energy band gaps and the functional group compositions of the detected flavonoids.

4-(Prop-2-yn-1-yloxy)benzene-1,2-dicarbonitrile

In the title compound, C11H6N2O, the complete molecule is generated by the application of crystallographic twofold symmetry (the molecule is disordered about this axis). The prop-2-yn-1-yl residue is slightly twisted out of the plane of the benzene ring [C—O—C—C torsion angle = 173.1 (3)°] and is orientated away from the nitrile substituents. In the crystal, supramolecular chains along the a axis, arising from C—H⋯N interactions, are connected into stacks along the c axis by π–π interactions between the benzene rings [centroid–centroid distance = 3.6978 (6) Å = length of the c axis].

Efficient ring-opening polymerization (ROP) of ε-caprolactone catalysed by isomeric pyridyl β-diketonate iron(iii) complexes

A series of Fe(III) complexes of β-diketonate ligands, 1-(2-pyridyl)-3-(3-pyridyl)-1,3-propanedione (L1), 1-(2-pyridyl)-3-(2-pyridyl)-1,3-propanedione (L2), 1-(2-pyridyl)-3-(4-pyridyl)-1,3-propanedione (L3), 1-(3-pyridyl)-3-(4-pyridyl)-1,3-propanedione (L4), 1-(3-pyridyl)-3-(3-pyridyl)-1,3-propanedione (L5) and 1-(4-pyridyl)-3-(4-pyridyl)-1,3-propanedione (L6), viz. [Fe(L1)3] (1), [Fe(L2)3] (2), [Fe(L3)3] (3), [Fe(L4)3] (4), [Fe(L5)3] (5) and [Fe(L6)3] (6) have been structurally characterized. All but one complex (1) catalyzed the ring-opening polymerization (ROP) of e-caprolactone (e-CL) in near quantitative yield at 110 °C to give polymers with relatively narrow polydispersities (PDI). The comparison of in situ reaction and a reaction with preformed 1 indicated that the latter was a better catalyst, giving a higher molecular weight. Complex 2 catalyzed this reaction in a more modest yield reflecting its greater thermal stability, shorter Fe–O bonds and minimal distortion in fold angle among the isomeric complexes, suggesting that ligand dissociation is important for catalytic activity.

Chemically modified carbon paste electrode for the detection of lead, cadmium and zinc ions

Purpose This paper aims to develop an inexpensive, portable, sensitive and environmentally friendly electrochemical sensor to quantify trace metals. Design/methodology/approach A sensor was constructed by modifying carbon paste electrode for the determination of lead, cadmium and zinc ions using square wave anodic stripping voltammetry (SWASV). The modified electrode was prepared by inserting homogeneous mixture of 2-hydroxy-acetophenonethiosemicarbazone, graphite powder and mineral oil. Various important parameters controlling the performance of the sensor were investigated and optimized. Electrochemical behavior of modified electrode was characterized by cyclic voltammetry. Findings Modified carbon pastes electrodes showed three distinct peaks at −0.50, −0.76 and −1.02 V vs silver/silver chloride corresponding to the oxidation of lead, cadmium and zinc ions at the electrode surface, respectively. The highest peak currents for all the metal ions under study were observed in the phosphate buffer solution at pH 1 with a deposition time of 70 s. The sensor exhibited linear behavior in the range of 0.25-12.5 μg mL-1 for lead and cadmium and 0.25-10.0 μg mL−1 for zinc. The limit of detection was calculated as 78.81, 96.17 and 91.88 ng mL−1 for Pb2+, Cd2+and Zn2+, respectively. The modified electrode exhibited good stability and repeatability. Originality/value A chemically modified electrode with Schiff base was applied to determine the content of cadmium, lead and zinc ions in aqueous solutions using SWASV.

(2Z)-3-Hy­droxy-1-(pyridin-2-yl)-3-(pyridin-3-yl)prop-2-en-1-one: crystal structure and Hirshfeld surface analysis

The title molecule, featuring an intramolecular O—H⋯O hydrogen bond, is non-planar as seen in the dihedral angle between the pyridyl rings of 7.45 (7)°. In the crystal, supramolecular chains are formed via π(pyridin-2-yl)–π(pyridin-3-yl) interactions.

4-[(1-Benzyl-1H-1,2,3-triazol-4-yl)meth­oxy]benzene-1,2-dicarbo­nitrile: crystal structure, Hirshfeld surface analysis and energy-minimization calculations

The terminal rings in the title compound have an anti disposition in contrast to a syn conformation calculated in the energy-minimized structure. Supramolecular layers in the ab plane and sustained by methylene-C—H⋯N(triazolyl) and carbonitrile-N⋯π(benzene) interactions feature in the molecular packing.

Crystal structure of bis­[(phenyl­methanamine-κN)(phthalocyaninato-κ4N)zinc] phenyl­methan­amine tris­olvate

A pentacoordinated Zn2+ ion is found in each independent complex molecule of the title compound; the asymmetric unit is completed by three conformationally flexible non-coordinating benzylamine molecules. Supramolecular layers sustained by N—H⋯N and N—H⋯π interactions are found in the crystal packing; these are connected by π–π contacts.

3-(Prop-2-yn-1-yl-oxy)phthalo-nitrile.

In the title compound, C11H6N2O {systematic name: 3-(prop-2-yn-1-yloxy)benzene-1,2-dicarbonitrile}, the 14 non-H atoms are approximately coplanar (r.m.s. deviation = 0.051 Å) with the terminal ethyne group being syn with the adjacent cyano residue. In the crystal, centrosymmetric dimers are connected by pairs of C—H⋯N interactions and these are linked into a supramolecular tape parallel to (1-30) via C—H⋯N interactions involving the same N atom as acceptor.

Dichlorido[2-(3,5-dimethyl-1H-pyrazol-1-yl-κN2)quinoline-κN]zinc

The ZnII atom in the title compound, [ZnCl2(C14H13N3)], is coordinated by a Cl2N2 donor set defined by quinoline and pyrazole N atoms of the chelating ligand and two Cl atoms. Distortions from the ideal tetrahedral geometry relate to the restricted bite angle of the chelating ligand [N—Zn—N = 78.54 (12)°]. In the crystal, molecules are connected into a three-dimensional structure by C—H⋯Cl interactions, involving both Cl atoms, and π–π interactions that occur between the pyrazole ring and each of the pyridine and benzene rings of the quinoline residue [intercentroid distances = 3.655 (2) and 3.676 (2) Å].

2-Hydrazinyl-quinoline.

In the title compound, C9H9N3, the 12 non-H atoms are essentially planar (r.m.s. deviation = 0.068 Å). The maximum deviation from planarity is reflected in the torsion angle between the β-N atom of the hydrazinyl residue and the quinolinyl N atom [N—N—C—N = −12.7 (3)°]; these atoms are syn. In the crystal, supramolecular layers in the bc plane are formed via N—H⋯N hydrogen bonds.