Thanks to thermal quenching we investigated the relaxation of the metastable state of Na(0.32)Co[Fe(CN)6](0.74).3.4H2O at low temperature. A self-accelerated process has been observed in agreement with the cooperative character of the system, responsible for the large thermal hysteresis of the charge-transfer-induced spin transition. The mean-field analysis of the relaxation is discussed with respect to the equilibrium properties. A sizable deviation from mean-field behavior is observed at the beginning of the relaxation process, which might be attributed to a preliminary structural relaxation of the quenched state.

A dye sensitized solar cell with lawsone dye and a ZnO photoanode exhibited a 0.68% power conversion efficiency. TD-DFT was used to explore the UV-Vis spectral features of lawsone.

A cationic iron(III) complex [FeIII(5-OMe-sal2trien]+ (where [H2(5-OMe-sal)2trien] was derived from triethylenetetramine and substituted salicylaldehyde), designed to undergo spin crossover, has been inserted in the layered MnPS3 host lattice. The magnetic properties of the resulting intercalation compound [Fe(5-OMe-sal2trien)]0.28Mn0.86PS3·nH2O have been characterized by 57Fe Mössbauer spectrometry and SQUID measurements. The untreated compound exhibits a sluggish thermal spin crossover over the range 200−300 K, but without hysteresis. Removing the co-intercalated water molecules from the compound dramatically affects its behavior and confers a broad hysteresis loop to the transition. The appearance of cooperativity is discussed in terms of elastic interactions and specific arrangement of the ferric complexes. Further interest arises from the spontaneous magnetization acquired by the intercalation compound below 36 K. The static internal magnetic field experienced by the iron sites affects the Mössbauer spectrum of the low-spin form of the inserted complex below T c.

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Synthesis and characterization of fluorescent benzo[a]phenoxazines viz., M-1B (10-chloro-6-methyl-7a,11a-dihydro-5H-benzo[a]phenoxazin-5-one), M-2B 6,10-dimethyl-7a,11a-dihydro-5H-benzo[a]phenoxazin-5-one), M-3B (6-methyl-7a,11a-dihydro-5H-benzo[a]phenoxazin-5-one) and benzo[a]phenthiazine, M-4B (6-methyl-5H-benzo[a]phenothiazin-5-one) were carried out. 1 H and 13 C chemical shifts were assigned from the 2DgHSQCAD NMR experiments. Compound M-1B crystallizes in the orthorhombic space group P2 1 2 1 2 1 , while M-2B and M-4B crystallize in the monoclinic space group P2 1 /c. The crystal network of M-1B showed slipped p-p stacking and Cl/Cl interactions, while M-2B facilitated ladder like p-p stacked polymeric chains. The C/S contacts were observed in the crystal environment of M-4B. All these structures possess C-H/O interactions. Electronic structure and charge distribution in terms of molecular electrostatic potential and frontier orbital analyses based on the MO6-2X based density functional theory further showed that monomer and dimer structures are in keeping with the single crystal X-ray data and provide insights for the growth of the crystal network. Antiproliferative activity of M-1B-M-4B was determined from the MTT assay against a human breast adenocarcinoma cell line (MCF-7), human carcinoma cell line (HeLa) and normal skin cell line. All these compounds showed significant cytotoxic activity against MCF-7 and HeLa by inducing apoptosis and thus can be viewed as potential candidates for antitumor therapy. Compounds M-2B and M-4B were further found to be topoisomerase II inhibitors.

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The relaxation of the metastable state of the spin-crossover compound [Fe(L)(2)](ClO(4))(2).H(2)O, with L = 2,6-bis(pyrazol-1-ylmethyl)pyridine, populated by the LIESST (light induced excited spin state trapping) effect, has been investigated by magnetic measurements. The time dependence of the relaxation curve at several temperatures, starting from different initial states, is in the shape of stretched exponentials, and the thermal variation of the photostationary state under constant photoexcitation is progressive and reversible. These features are satisfactorily modeled by considering noninteracting two-level systems with a distribution of activation energies. A suggested origin for the distribution is the conformational flexibility of the nonplanar heterocyclic ligands. The effect of the intensity distribution during the LIESST process is also accounted for in a simple way.