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4,4-Dimethyl-2-(3-chloro-2-methyl-1-propenyl)-2-oxazoline has been synthesized and deprotonated with LDA in THF to give the corresponding lithiated species, which has been found to react α -regioselectively with NH 4 Cl and alkyl halides, and γ- regioselectively with carbonyl compounds to afford α-protonated (or α-alkyl-substituted) regioisomers and vinyl epoxides, respectively. The Z diastereoselectivity of both the protonation and the alkylation reactions was usually found to increase with the temperature. Ab initio calculations, performed on both the naked lithium salt and the corresponding solvated form, support the observed regioselectivity. [ABSTRACT FROM AUTHOR]

Dihydroxy functionalised zwitterionic push-pull chromophores have been introduced in 3-glycidoxypropyltrimethoxysilane, tetraethylorthosilicate and N-[(3-trimethoxysilyl)propyl]ethylenediamine derived hybrid materials. Hybrid films have been deposited as thick layers via spin-coating. The amine groups introduced with the organically modified alkoxide bearing amine functionalities have been found to have an effective scavenger effect of the dye photobleaching.The addition, during the synthesis of the precursor sol, of N-hydroxyl carbazole has allowed to reach up to 20% of chromophore concentration avoiding the formation of aggregates within the matrix. The NLO properties of the material, after poling, have shown a good temporal stability, with retention of ca. 70% of the initial signal value, after several months, providing a d33 value of ∼50÷70 pm V−1 at the wavelength of 1.064 μm. [Copyright &y& Elsevier]

Graphical abstract The synthesis and characterization of two simple Ruthenium(II) thiocyanate free complexes and the exploitation of a new carbon doped anatase TiO 2 paste in dye-sensitized solar cells (DSSCs) photoanode are described. Highlights • Synthesis of interesting Ru-thiocyanate free dyes. • Synthesis of a new carbon doped anatase TiO 2 paste. • The proper combination of Ru dyes and C-doped titania affords working DSSC. Abstract The synthesis and characterization of two simple Ruthenium(II) complexes of the type [Ru(X^N) 2 (4,4′-dicarboxybipyridine)]+ (with X C, X^N benzoquinolinate, 1 ; with X N, X^N 2-pyridyl tetrazolate, 2) and the exploitation of a new carbon doped anatase TiO 2 paste in dye-sensitized solar cells (DSSCs) photoanode are described. In particular, glucose (C 6 H 12 O 6) is used as a new chemical eco-friendly C-dopant during the doping process of anatase TiO 2 nanoparticles. The proper combination of Ru(II) sensitizers and C-doped titania can afford efficient DSSC photoanodes. All the relevant photovoltaic parameters have been determined. [ABSTRACT FROM AUTHOR]

Abstract The synthesis, photophysical and electrochemical characterization, theoretical calculations and photovoltaic studies of a push-pull dye with an unconventional nonplanar tetrathiahelicene π−spacer between the donor-acceptor groups, are reported. The molecule exhibits suitable HOMO LUMO levels to be used in DSSC. The presence of the donor-acceptor helical architecture allows the internal charge transfer and subsequent electron injection to the conduction band of TiO 2 leading to the good photocurrent value of 4.6 mA cm−2. Highlights • A novel push-pull system based on a chiral helical thiophene-containing helicene as π-spacer has been described. • This dye exhibits suitable HOMO-LUMO levels to be used in DSSC. • Donor-acceptor helical architecture allow the internal charge transfer and subsequent electron injection to the TiO 2. • This dye exhibits very good performances in DSSC. [ABSTRACT FROM AUTHOR]

We report here the first example of a covalent functional nanocarbon hybrid based on a benchmark metal-free donor-π-acceptor (D-π-A) dye and reduced graphene oxide (RGO). The dyad, prepared by direct arylation of the RGO surface by means of an aniline derivative of the D-π-A species, has been thoroughly characterized in terms of dye loading percentage and spectroscopic properties, in comparison with the reference free dye, pristine RGO, and with an analogous non-covalent dye-RGO hybrid. When used as a photosensitizing agent in dye-sensitized solar cells (DSSC), the covalent hybrid demonstrated lower photovoltaic performances compared to the cell with the reference dye, a result that was mostly ascribed to the lower dye content of the former. Furthermore, the RGO based sensitizer showed stronger binding to the semiconductor oxide in comparison to the reference dye, paving the way to a new generation of DSSC photoanodes with improved chemical stability. This work demonstrates the full potential of the new class of hybrid sensitizers to equal or even exceed the photovoltaic performances achieved by standard organic photovoltaic sensitizers once molecular engineering of the functional nanocarbon hybrid has been refined. [ABSTRACT FROM AUTHOR]

A series of push–pull triarylamine organic dyes containing the benzo[1,2- b :4,5- b ′]dithiophene unit as a spacer and bearing alkyl chains in different positions of the molecule were synthesized. The new dyes 1 – 4 were characterized by optical and electrochemical measurements and density functional theory calculations and used as sensitizers in liquid dye-sensitized solar cells. The effect of alkyl chain position on dye properties and performances was investigated and dye 1 , bearing two 3,7-dimethyloctyl groups on the benzodithiophene core, exhibited the best behaviour in term of light absorption and cell performance (PCE of 6.6%, to be compared with a PCE of 8.1% for N719-based device). The efficiency of the DSSC was highly dependent on the solvent used for the dye-sensitizing bath, which affects the position of the COOH/COO − equilibrium. [ABSTRACT FROM AUTHOR]

Thiocyanate-free Ru(II) complexes as photosensitizers for dye-sensitized solar cells (DSSCs) are presented. These classes of complexes have gained in recent times increasing interest due to their more favorable long-term stability compared to conventional thiocyanate-based complexes such as benchmark dyes N719 and Z907. Here two classes of thiocyanate-free ruthenium(II) complexes have been reviewed: (a) bis-bipyridyl complexes bearing an ancillary cyclometallated bidentate ligand; (b) bipyridyl complexes bearing non-cyclometallated bidentate ancillary ligands. The article briefly outlines design strategies and optical and photovoltaic properties of these two families of ruthenium dyes. Although their photovoltaic performances is not as high as that of N719, recent increasing efforts by many research groups have allowed to achieve favorable light harvesting abilities, device photocurrents, and top-ranked power conversion efficiencies in combination with superior long-term stabilities, paving the way to efficient solar devices endowed with long-term chemical and thermal stability for viable large-scale commercialization of DSSCs. [ABSTRACT FROM AUTHOR]

Abstract: The two-photon absorption (TPA) properties of 4,4′-bis(para-di-n-butylaminostyryl)-2,2′-bipyridine (NBu2bipy) and related dipolar ([ZnY2(NBu2bipy)] (Y=Cl, CF3CO2), [Zn(2,2′-bipyridine)2(NBu2bipy)][PF6]2) and octupolar ([Zn(NBu2bipy)3][PF6]2) complexes were investigated by the two-photon emission (TPE) technique in a femtosecond regime, working in the 730–930nm spectral range. We found, in contrast with previous literature data, that the TPA enhancement upon coordination of a TPA active ligand to a metal center may be larger in the dipolar rather than the corresponding octupolar complex, the response being easily modulated by the choice of the ancillary ligands. [Copyright &y& Elsevier]

Abstract: Hybrid organic–inorganic materials doped with zwitterionic push–pull chromophores with high hyperpolarizability have been synthesized via sol–gel, based on glycidoxypropyltrimethoxysilane (GPTMS) and glycidoxypropylmethyldimethoxysilane (GDMMS). Homogeneous films doped with chromophores, have been obtained using N-hydroxyethylcarbazole as a physical spacer avoiding dye aggregation. The waveguiding properties of the spin-coated doped films electrically poled in N2 atmosphere showing second harmonic generation measurements, have been preliminarily measured by m-line spectroscopy before and after poling; the feasibility of channel waveguiding structures has been demonstrated. [Copyright &y& Elsevier]