pH-Dependent spectroscopic and luminescent properties, and metal-ion recognition studies of Re(I) complexes containing 2-(2'-pyridyl)benzimidazole and 2-(2'-pyridyl)benzimidazolate.

A series of Re(I) complexes, [Re(CO)(3)Cl(HPB)] (1), [Re(CO)(3)(PB)H(2)O] (2), [Re(CO)(3)(NO(3))(PB-AuPPh(3))] (3), and [Re(CO)(3)(NO(3))(PB)Au(dppm-H)Au](2) (4) [HPB = 2-(2'-pyridyl)benzimidazole; dppm = 2,2'-bis(diphenylphosphinomethane)], have been synthesized and characterized by X-ray diffraction. Complex 1, which exhibits interesting pH-dependent spectroscopic and luminescent properties, was prepared by reacting Re(CO)(5)Cl with an equimolar amount of 2-(2'-pyridyl)benzimidazole. The imidazole unit in complex 1 can be deprotonated to form the imidazolate unit to give complex 2. Addition of 1 equiv of AuPPh(3)(NO(3)) to complex 2 led to the formation of a heteronuclear complex 3. Addition of a half an equivalent of dppm(Au(NO(3)))(2) to complex 2 yielded 4. In both 3 and 4, the imidazolate unit acts as a multinuclear bridging ligand. Complex 4 is a rare and remarkable example of a Re(2)Au(4) aggregate in combination with µ(3)-bridging 2-(2'-pyridyl)benzimidazolate. Finally, complex 2 has been used to examine the Hg(2+)-recognition event among group 12 metal ions. Its reversibility and selectivity toward Hg(2+) are also examined.

Organic dyes with remarkably high absorptivity; all solid-state dye sensitized solar cell and role of fluorine substitution.

A series of new organic D-pi-A dyes, A1, A2-H and A2-F, possessing a remarkably high absorption extinction coefficient of epsilon > 5.0 x 10(4) M(-1) cm(-1) at peak wavelength were synthesized, among which, A2-F having a key fluorine substitution attains excellent all solid-state DSSC performance, with optimized parameters of eta = 4.86%, J(SC) = 7.52 mA cm(-2), V(OC) = 0.91 V, and FF = 0.71.

Design and synthesis of trithiophene-bound excited-state intramolecular proton transfer dye: enhancement on the performance of bulk heterojunction solar cells.

In an aim to harvest UV-near-visible (360-440 nm) photons as well as to increase the morphology in the bulk heterojunction solar cells, we report herein the strategic design, synthesis, and characterization of a novel excited-state intramolecular proton-transfer dye, 3-hydroxy-2-(5-(5-(5-(3-hydroxy-4-oxo-4H-chromen-2-yl)thiophen-2-yl)thiophen-2-yl)thiophen-2-yl)-4H-chromen-4-one (FT), which bears two key functional groups, namely 3-hydroxychromone chromophore and trithiophene backbone and is then exploited into the blends of regioregular poly(3-hexylthiophene) (RR-P3HT) and phenyl-C(61)-butyric acid methyl ester (PCBM). FT acts as an excellent UV-near visible absorber, which then undergoes excited-state intramolecular proton transfer, giving rise to an orange-red proton-transfer emission that was reabsorbed by P3HT via a Forster type of energy transfer. Introduction of FT to P3HT/PCBM blend films also improves the morphology of phase separated structure, in particular, enhances the interaction of P3HT chains and the hole mobility. In this work, under the optimized condition of P3HT: PCBM:FT of 15:9:2 in weight ratio, the best performance of the device B-FT2 revealed consistent enhancements in the efficiency (eta) 4.28% and short-circuit current (J(sc)) 12.53 mAcm(-2), which are higher than that (3.68% and 10.28 mAcm(-2)) of the best performance of the control device B (P3HT:PCBM 15:9 in weight ratio) by 16 and 22%, respectively.

Photoisomerization of a maleonitrile-type salen Schiff base and its application in fine-tuning infinite coordination polymers.

Strategically designed salen ligand 2,3-bis[4-(di-p-tolylamino)-2-hydroxybenzylideneamino]maleonitrile (1), which has pronounced excited-state charge-transfer properties, shows a previously unrecognized form of photoisomerization. On electronic excitation (denoted by an asterisk), 1Z*-->1E isomerization takes place by rotation about the C2--C3 bond, which takes on single-bond character due to the charge-transfer reaction. The isomerization takes place nonadiabatically from the excited-state (1Z) to the ground-state (1E) potential-energy surface in the singlet manifold; 1Z and 1E are neither thermally inconvertible at ambient temperature (25-30 degrees C), nor does photoinduced reverse 1E*-->1Z (or 1Z*) isomerization occur. Isomers 1Z and 1E show very different coordination chemistry towards a Zn(II) precursor. More prominent coordination chemistry is evidenced by a derivative of 1 bearing a carboxyl group, namely, N,N'-dicyanoethenebis(salicylideneimine)dicarboxylic acid (2). Applying 2Z and its photoinduced isomer 2E as building blocks, we then demonstrate remarkable differences in morphology (sphere- and needlelike nanostructure, respectively) of their infinite coordination polymers with Zn(II).

Fluorescent protein red Kaede chromophore; one-step, high-yield synthesis and potential application for solar cells.

The one-step condensation between the Green Fluorescence Protein (GFP) chromophore and 1H-imidazole-5-carbaldehyde catalyzed by ZnCl(2) proved to be a facile method to synthesize the red Kaede chromophore and its derivatives (1a-d, 2, and 3 > 70%), among which 1a then demonstrated its potential as a dye in solar cell, with a moderate conversion efficiency (eta) of 3.04%.

Neutral, panchromatic Ru(II) terpyridine sensitizers bearing pyridine pyrazolate chelates with superior DSSC performance.

A new series of neutral, panchromatic Ru(II) terpyridine sensitizers (PRT1-PRT4) exhibit much higher molar extinction coefficients at 400-550 nm and superior DSSC performance in terms of conversion efficiency (eta = 10.05 for PRT4) and stability.

Novel single-crystal-to-single-crystal anion exchange and self-assembly of luminescent d(10) metal (Cd(II), Zn(II), and Cu(I)) complexes containing C(3)-symmetrical ligands.

Ligands L1 and L2' (L1=N,N',N''-tris(4-pyridyl)trimesic amide, L2'=N,N',N''-tris(3-pyridinyl)-1,3,5-benzenetricarboxamide) belonging to an interesting family of tripyridyltriamides with C(3)-symmetry have been utilized to construct 3D porous or hydrogen-bonded frameworks. Through a novel single-crystal-to-single-crystal anion-exchange process, [Cd(L1)(2)(ClO(4))(2)](n) (1c) can be obtained from [Cd(L1)(2)Cl(2)](n) (1b) in the presence of ClO(4)(-) anions. This anion-exchange process is highly selective and only the substitution of Cl(-) by ClO(4)(-) or PF(6)(-) could be realized; Cl(-) was found not to be substituted by BPh(4)(-). This demonstrates that the exchange process depends on the size of the anions in relation to the size of the cavities in the host material (ca. 7.5 A). In addition, the anion-exchange properties of 1 b have also been investigated by means of powder X-ray diffraction (PXRD), elemental analysis (EA), and infrared absorption spectroscopy (IR). Structurally, [Zn(L1)(NO(3))(2)](n)(2) consists of a 2D coordination network with five-coordinate Zn(II) ions. Surprisingly, different trigonal-bipyramidal Zn(II) ions propagate to form distinct respective sheet structures, A and B, which are packed in an A-B-A-B manner in the crystal lattice, and these are hydrogen-bonded to give a 3D extended framework. The molecular structure of [CuI(L2')](n)(3) shows that the Cu(I) ion adopts a distorted tetrahedral geometry, and 3 also forms a 2D coordination network. Significantly, this 2D coordination network is further assembled into a remarkable 3D homochiral framework through triple hydrogen bonding and pi...pi interactions. All of these 3D coordination polymers and/or hydrogen-bonded frameworks are luminescent in the solid state, and their solid-state luminescent properties have been investigated at room temperature and/or at 77 K.

Crystal-engineering studies of coordination polymers and a molecular-looped complex containing dipyridyl-amide ligands.

We report herein crystal-engineering studies of coordination polymers and a molecular-looped complex containing two dipyridyl-amide ligands, 1,3-bis-pyridin-4-ylmethyl urea (L1) and N,N'-bis-4-methylpyridyl oxalamide (L2). The reaction of Cd(OAc)2 with L1 gives rise to [Cd(OAc)2(L1)]n (1), a 1-D chain through coordination to two L1 and two acetate ligands, and then the axial coordination to one urea's carbonyl group through the third L1 ligand leads 1 to form "a dimer of 1-D chains". With a slight change in the structural backbone from L1 to L2, the reaction of L2 with Cd(OAc)2 gives [Cd(OAc)2(L2)(H2O)]n (2), a 1-D chain structure. The reaction of Cd(NO3)2, instead of Cd(OAc)2, with L2 gives [Cd(NO3)2(L2)3/2]n (3), where the coordinated-anion effect on the assembly process has been observed for 2 and 3. The former forms a 1-D chain structure, and the latter, a 2-D sheet structure, depending on the coordinated anions used. [HgCl2(L1)]n (4) and [CuCl2(L2)]n (5), which are 1-D chain structures, show tetrahedral [Hg(II)] and square-planar [Cu(II)] centers, respectively. Surprisingly, 4 shows a typical amide-amide hydrogen bonding and 5 shows none. Instead, a hydrogen-bonding interaction between Cl and the amide group is observed in 5. Finally, the different structural conformation of L2 (a syn or anti form) leads to the formation of different structural motifs, coordination polymers (2, 3, and 5 with an anti form), and a macrocycle ([Pd(PPy)(L2)]2(ClO4)2 (6) with a syn form, PPy = 2-phenylpyridine). Each side of the boat form of 6 (pseudo-cyclohexane) ranges from 6.12 to 6.39 A, and the molecular loop is further hydrogen-bonded to stack into a 1-D hydrogen-bonded framework with a ladder pattern through amide-amide hydrogen bonding. Interestingly, one ClO4- anion is encapsulated inside the cavity through multiple CH...O interactions.