Push-pull terpyridine derivatives 3 were synthesized and characterized in order to study the variations produced in their optical and electronic properties by linking different (hetero)aromatic electron donor moieties at 4′position of the electron deficient terpyridine moiety. The final donor-acceptor systems 3a-g were synthesized in fair to good yields by Kröhnke condensation of the precursor aldehydes 1, with 2-acetylpyridine 2. Hyper-Rayleigh scattering in dioxane solutions using a fundamental wavelength of 1064 nm was employed to evaluate their second-order nonlinear optical properties. Terpyridine derivative 3g functionalized with the 9-ethyl-9Hcarbazolyl group exhibited the largest first hyperpolarizability (β = 610 × 10 −30 esu, using the T convention) thus indicating its potential application as a second harmonic generation (SHG) chromophore. Terpyridine derivatives 3 were also used as ligands for the synthesis of novel [Ru II (tpy)(NCS) 3 ]complexes, prepared in good yields by a two-step procedure involving the preparation of [Ru III (tpy)(Cl 3 )] as intermediates. Ruthenium II complexes display a broad absorption in the visible range, accounting for their very dark color. Their redox behaviour is mainly characterized by the Ru II -Ru III oxidation and by the ligand-centered reduction, whose potentials can be finely tuned by the electronic properties of the aromatic substituents on the terpyridine ligand. Hyper-Rayleigh scattering in methanol solutions using a fundamental wavelength of 1064 nm was also employed to evaluate their second order nonlinear optical properties.
Four novel heterocycle dyes 3a-d were synthesized in order to study the variations produced in the optical, electronic and photovoltaic properties by substitution of different electron-rich heterocyclic groups to the thieno[3,2-b]thiophene system. The final push-pull conjugated dyes 3a-d were synthesized by Suzuki-Miyaura coupling reaction followed by Knoevenagel condensation of the corresponding aldehyde precursors with cyanoacrylic acid 2a-d. These new push-pull systems are based on a thieno[3,2-b]thiophene spacer, a cyanoacetic acid anchoring group and several electron-rich heterocycles (thiophene, pyrrole and furan) as donor groups. The multidisciplinary study concerning the optical, redox and photovoltaic characterization of the dyes reveals that compound 3b bearing a hexyl-bithiophene donor group/heterocyclic spacer exhibits the best overall conversion efficiency (2.49%) as sensitizer in nanocrystalline TiO 2 dye sensitized solar cells. Co-adsorption studies between N719 and 3b revealed that upon addition of N719 co-adsorbent, the optimized cell efficiencies were improved by 16e77%. The best efficiency was 4.40%, corresponding to 54% of the photovoltaic performance of the N719-based DSSC fabricated and measured under similar conditions.
10À30 esu, using the T convention) and high decomposition temperature (T d ¼ 312 C), thus indicating its potential application as a useful material for incorporation into non-linear optical devices.
A series of push-pull aryl-bithiophene based systems 2-3 were designed and synthesized in order to understand how structural modifications influence the electronic, linear and nonlinear optical properties. The push-pull conjugated chromophores 2-3 bear a bithiophene spacer conjugated with a phenyl ring functionalized with N,Ndialkylamino electron-donor groups together with cyanoacetic or rhodanine-3-acetic acid acceptor groups. Theoretical (DFT calculations) and experimental studies were carried out to obtain information on conformation, electronic structure, electron distribution, dipolar moment, and molecular nonlinearity response of the push-pull bithiophene derivatives. This multidisciplinary study revealed that chromophore 2e exhibits the highest value for hyperpolarizability β (10440 × 10 −30 esu) due to the strong electron donating ability of the N,N-dimethylamino group, and the ethyne linker that not only lengthens the π-conjugation path but also grants less distortion to the system.
a b s t r a c tFive push-pull heterocyclic dyes 4e7, and 9 were synthesized and characterized in order to study the variations in the optical, electronic and photovoltaic properties induced by structural modifications, i.e. different spacer units and anchoring groups. The final push-pull conjugated dyes 6e7 and 9 are formed by a N,N-dimethylaniline donor moiety conjugated with bithiophene, ethynyl-bithiophene or ethynylthieno[3,2-b]thiophene spacers and cyanoacetic acid or rhodanine-3-acetic acid as anchoring group. The synthesis of the precursor aldehydes 4e5 was accomplished through a Sonogashira coupling, on the other hand, compound 8 was prepared by Suzuki coupling. Knoevenagel condensation of aldehydes 4, 5 and 8 with cyanoacetic acid or rhodamine-3-acetic acid afforded the final push-pull dyes 6, 7 and 9. Information on conformation, electronic structure and electron distribution was obtained by DFT and TDDFT calculations. This multidisciplinary study regarding the evaluation of the optical, redox and photovoltaic properties of the dyes reveals that compound 7, bearing an ethynyl-bithiophene spacer conjugated with a cyanoacetic acid anchoring group, has the highest conversion efficiency (3.51%) as dye sensitizer in nanocrystalline TiO 2 solar cells. Co-adsorption studies were also performed for dyes 6e7 with N719 as co-adsorbent, and this enhanced dye efficiencies by 33e45%. The best cell performance was obtained by co-adsorbing N719 and dye 7 (75/25 vol%) with 4.66% efficiency.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.