We have synthesized a series of new D−π−A compounds that feature various electron donors and a fixed benzothiazolyl unit as an electron acceptor. The crystal structure of compound 3 [trans,trans-2-{4-[(4-N-carbazolyl)styryl]styryl}-1,3-benzothiazole, CSSB] was determined. All these compounds show high fluorescence quantum yields and 3 in toluene gives the most intense blue emission around 450 nm with a quantum yield of Φ = 0.69. When excited at 800 nm by a Ti: sapphire femtosecond laser, these compounds exhibit strong two-photon-excited fluorescence (TPEF) in the blue-to-orange region. The measured TPEF cross-section of compound 2 [trans,trans-2-{4-[4-(N,N-diphenylamino)styryl]- styryl}-1,3-benzothiazole, DPSSB], for example, is about 6.1 times that of Coumarin 307. hotophysical data indicate that these compounds are polar in the ground state and have an enhanced polarity in the excited state, and that the electron donating ability of a dialkylamino group is much stronger than that of a diarylamino group.

A new molecular conductor PyH[Pd(dmit)2]2 (PyH=pyridinium, dmit=2-thioxo-1,3-dithiole-4,5-dithiolato) has been synthesized and structurally investigated. The room temperature conductivity at a certain direction on (001) plane was measured to be as high as a 2

We have synthesized two new organic salts, trans-4-[p-(N-hydroxyethyl-N-methylamino)styryl]-Nmethylpyridinium toluene-p-sulfonate (abbreviated as HMASPS) and trans-4-[p-(N-hydroxyethyl-Nethylamino) styryl]-N-methylpyridinium toluene-p-sulfonate (abbreviated as HEASPS). X-Ray iffraction analyses reveal that HMASPS crystal belongs to the P21/n space group, with water olecules co-crystallized in the crystal and forming the monohydrate with the formula of C17H21N2Oz?C7H7O3S2?H2O, while HEASPS belongs to the P1

Three s-triazine derivatives have been synthesized and their structures been de-termined. These are Compound I: 2,4-Dimethyl-6-(p-N, N-dimethylaminostyryl)-s-triazine (ab-breviated to NMe-1), Compound II: 2, 4-Dimethyl-6-(p-N, N-diethylaminostyryl)-s-triazine (to NEt-1), and Compound III: 2-Methyl-4, 6-bis(p-N, N-dimethylaminostyryl)-s-triazine (NMe-2). NMe-1 and NEt-1 molecules belong to the D-π-A type with a one-dimensional charge-transfer character. NMe-1 crystallize to centrosymmetric 1P space group, while NEt-1 to non-centro- sym- metric polar Cc space group with all of the molecular charge-transfer axes taking the same orientation. Under the irradiation of 1064 nm fundamental laser, NEt-1 powder crystals radiate a 2-order harmonic light with an intensity 46.8 times that of urea. The Λ typed NMe-2 molecule, which has a two-dimensional charge-transfer character, crystallize to polar P21 space group. Its powder crystals exhibit a 2-order harmonic intensity 46.2 times that of urea. The quantum chemical calculations and tensor analyses have been carried out to reveal the dependence of the macro 2-order nonlinear optical (NLO) efficiency on the micro 2-order NLO coefficients (β) and on the crystalline packing styles.

The synthesis, structure, and fluorescence properties of a series of new donor -π- acceptor (D-π-A) type compounds, with a trivalent boron, protected by two mesityl groups, as acceptor, and with various typical donors and different-conjugated bridges, are reported. All these stable organoboron compounds show intense singlephoton excited fluorescence (SPEF) and two-photon excited fluorescence (TPEF) in a wide spectral range from blue to green, with the spectral peak position of the SPEF being basically the same as that of the TPEF. The remarkably strong C B(mesityl)2 bonding, and the well-conjugated -system, shown in X-ray crystal structures of two compounds, indicate some charge transfer features of the ground state. Meanwhile, spectral data indicate that the charge transfer from donor to acceptor is greatly enhanced in the excited states. Based on typical structural data and comprehensive spectral data, the following structure-property relationships can be drawn: 1) the moderate arylamino donor can more effectively enhance the SPEF and TPEF intensities than can the strong alkylamino donor; 2) stilbene is a better-bridge than styrylthiophene for its capability of enhancing and blueshifting the SPEF and TPEF of the corresponding D-π-A compounds; and 3) when compared to its boron-free precursors and other analogues, -B(mesityl) 2 invariably and consistently acts as an effective SPEF and TPEF fluorophore in all this series of organoboron compounds, which may result from its strong-electron-withdrawing and charge transfer-inducing nature in the ground-state and, more dominantly, in the excited-state. Combining all the above positive structure factors, trans-4-N,N-diphenylamino-4-dimesitylborylstilbene (compound 3) stands out as the optimized green SPEF and TPEF emitter. This compound exhibits an SPEF quantum yield of 0.91 at 522 nm in THF, a TPEF cross-section that is an order of magnitude larger than that of its boron-free precursor upon excitation by 800nm femto-second laser pulses, and a two-photon absorption section of 3.0 10 48 cm4 s. In the blue light region, trans-4 -N-carbazolyl-4-dimesitylborylstilbene (compound 4) shows significant SPEF and TPEF properties, with 0.79 at 464 nm in THF and a large value, which is five times that of fluorescein upon excitation by 740 nm femto-second laser pulses.