Effect of modified donor units on molecular hyperpolarizability of thienyl-vinylene nonlinear optical chromophores

Highly efficient and thermally stable nonlinear optical chromophores based on the phenyl vinylene thiophene vinylene (FTC) donor-π-acceptor structure have been synthesized and investigated. The donor part of the chromophores was modified with additional donor units, resulting in the enhanced nonlinear optical property with large molecular hyperpolarizability. Hyper-Rayleigh scattering measurement indicated nearly threefold increase of the molecular hyperpolarizability for novel chromophores compared with the benchmark FTC chromophore. Furthermore, measurement of the electro-optic coefficient confirmed that enhancement of microscopic molecular hyperpolarizability of the chromophores can be effectively translated into macroscopic electro-optic property. Measured electro-optic coefficients were nearly twofold larger than that for the benchmark FTC. Thermal analysis indicated that the synthesized chromophores showed the excellent temperature stability with decomposition temperatures up to 280 °C.     

New bichromophoric-2,2′-bipyridines: synthesis and optical properties

The synthesis and characterization of new unsymmetrically substituted bipyridyl-based chromophores featuring π-conjugated donor, acceptor or photoisomerizable backbones are reported. Their absorption and emission properties are discussed in comparison to those of the parent ligands.     

Distyryl-boradiazaindacenes: facile synthesis of novel near IR emitting fluorophores

Boradiazaindacenes with methyl substituents at 3 and 5 positions were for the first time shown to undergo efficient double condensation reactions with an aromatic aldehyde yielding a series of extended conjugation dyes. These new fluorophores have absorption maxima in the range of 650-660 nm. The dyes reported here have large quantum yields with 20 nm Stokes' shifted emission peaks. The straightforward synthesis of such red shifted BODIPY derivatives is important in relation to the synthesis of novel and useful fluorescent chemosensors. In addition, this facile transformation may make these new fluorophores' building blocks in the construction of large functional supramolecular systems.     

Light Harvesting and Energy Transfer in Novel Convergently Constructed Dendrimers

By the attachment of interacting laser dyes to the chain ends and focal point of a dendritic macromolecule it is possible to funnel energy harvested by the large peripheral antenna of the dendrimer (see picture on the left) efficiently and directly to the central fluorescent core (picture in the middle) by a process that does not involve the dendrimer inner backbone. The energy is then emitted as a narrow band of fluorescent radiation from the core (picture on the right).     

取代基对二噻吩并噻吩衍生物的双光子吸收性质的影响

利用ZINDO/SOS方法, 从理论上研究了对称和不对称取代两种情况下, 取代基对二噻吩并噻吩衍生物单双光子吸收性质的影响. 结果表明, 所设计的噻吩类分子具有较大的双光子吸收截面, 且双受体取代比双给体取代更有利于增大分子的双光子吸收截面. 同时发现, 此类分子受体取代可以显著增加波长较短的双光子峰附近的双光子吸收, 而给体取代则可以改善波长较长吸收峰附近的双光子吸收.     

Unsymmetrically substituted four-armed tolanes: new multichromophoric molecules

The selective synthesis of a four-armed tolane with different fluorescent chromophores that are asymmetrically distributed is described. Its optical absorption and emission properties were examined. This multichromophoric molecule exhibits a charge-transfer pathway that has a pronounced effect on the overall optical properties, together with an energy transfer process. Appropriate basic centers are present, meaning that the energy transfer processes can be stopped by the addition of acid—a process that makes this system a fluorescent pH-sensor.     

Synthesis and nonlinear optical properties of linear and Λ-shaped pyranone-based chromophores

New, pyranone-based chromophores were synthesized and their (nonlinear) optical properties were measured. The chromophores were prepared by first condensing an electron withdrawing group with pyranone, followed by reaction with an aldehyde-functionalized π-conjugated bridged donor molecule. This approach enables one to easily incorporate the pyranone moiety and to prepare both linear and Λ-shaped chromophores. The (nonlinear) optical properties were measured using femtosecond hyper-Rayleigh scattering. These measurements demonstrated the advantages of this approach.     

Synthesis of unsymmetrical 4-oxo-2-vinyl-4H-chromene-3-carbonitrile dyes via Knoevenagel reaction

New 4-oxo-2-vinyl-4H-chromene-3-carbonitrile derivatives have been synthesized by the Knoevenagel reaction of 2-methyl-4-oxo-4H-chromene-3-carbonitrile with aromatic and heteroaromatic aldehydes. Spectral properties of the obtained compounds have been studied.     

Optical Spin Polarization of a Narrow-Linewidth Electron-Spin Qubit in a Chromophore/Stable-Radical System

Photoexcited organic chromophores appended to stable radicals can serve as qubit and/or qudit candidates for quantum information applications. 1,6,7,12-Tetra-(4-tert-butylphenoxy)-perylene-3,4 : 9,10-bis(dicarboximide) (tpPDI) linked to a partially deuterated α,γ-bisdiphenylene-β-phenylallyl radical (BDPA-d₁₆) was synthesized and characterized by time-resolved optical and electron paramagnetic resonance (EPR) spectroscopies. Photoexcitation of tpPDI-BDPA-d₁₆ results in ultrafast radical-enhanced intersystem crossing to produce a quartet state ( Q ) followed by formation of a spin-polarized doublet ground state ( D ₀). Pulse-EPR experiments confirmed the spin multiplicity of Q and yielded coherence times of T_m=2.1±0.1 μs and 2.8±0.2 μs for Q and D ₀, respectively. BDPA-d₁₆ eliminates the dominant ¹H hyperfine couplings, resulting in a single narrow line for both the Q and D ₀ states, which enhances the spectral resolution needed for good qubit addressability.     

A Molecular Chameleon: Chromophoric Sensing by a Self-Complexing Molecular Assembly

A color change from purple to green takes place on addition of tetrathiafulvalene (TTF) to the macrobicyclic receptor 1 ⁴⁺, which is composed of a cyclobis(paraquat-p-phenylene) tetracation that shares one of its paraphenylene rings with a 1,5-naphthoparaphenylene-[36]crown-10 macrocycle. The TTF molecule forces the macrobicycle to turn inside out (see schematic drawing below) and displaces the self-complexed 1,5-dioxynaphthalene ring system from the center of the tetracationic cyclophane.