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Highly efficient and thermally stable nonlinear optical chromophores based on the same thiophene π-conjugation and tricyanofuran acceptor (TCF) possessing different isolation groups attached to electron-donating moiety have been synthesized and systematically investigated in this paper. Density functional theory (DFT) was used to calculate the HOMO–LUMO energy gaps and first-order hyperpolarizability (β) of these chromophores. These new chromophores showed excellent thermal stability with their decomposition temperatures all above 250 °C. Most importantly, the molecular hyperpolarizability of these chromophores can be effectively translated into large electro-optic (EO) coefficients (r 33 ) in poled polymers. The doped films-B containing 25 wt % chromophore F1 displayed an r 33 value of 52 pm/V at 1310 nm, and the doped films-C containing F2 showed a value of 91 pm/V at the concentration of 35 wt %. These values are all much higher than the traditional FTC chromophore (39 pm/V). These results revealed that the introduced isolation group can reduce intermolecular electrostatic interactions thus enhance the macroscopic EO activity. Besides, the position of the isolation group plays an equally important role in achieving the ultra large EO coefficients of materials. These properties, together with the good solubility, suggest the potential use of these new chromophores as advanced materials devices. [ABSTRACT FROM AUTHOR]

Three chromophores with tricyanofuran and tricyanopyrroline electron acceptors were synthesized and doped in high glass transition temperature ( T) polymer poly( N-(4-acetoxylphenyl)maleimide-co-styrene, NAPMI-co-ST). The electro-optic (EO), optical, and thermal properties of the doped poly(NAPMI-co-ST) were characterized and discussed. After being corona poled under 12 kV, this high T polymer material showed excellent EO activity and thermal stability. The highest EO coefficient ( r) reached 48.2 pm V (1,310 nm) and could remain 90 % of the original value for 100 h at 85 °C. The EO coefficient was relatively higher compared with other high T EO polymers. The thermal stability was also very good and the manufacture process was convenient and applicable for device fabrication. [ABSTRACT FROM AUTHOR]

Abstract: A novel nunchaku-like organic second order nonlinear optical chromophore containing a D–π–A backbone and a rigid biphenylene unit was prepared. The UV–vis absorption spectra studies demonstrated that the large rigid structure could suppress dipole–dipole interactions effectively. The electro-optic coefficient of a poled film containing 20% wt of the new dye doped in amorphous polycarbonate afforded a value of 39 pm/V at 1310 nm. Compared with results obtained from a similar D–π–A chromophore without the rigid isolated group, the new dye gave better performance. Moreover, the electro-optic film prepared with the new dye gave greater temporal stability, compared to a similar D–π–A doped poled film that was reported previously. These results indicated that the introduction of a biphenylene group could effectively reduce the intermolecular electrostatic interactions and aid the alignment of the chromophores. [Copyright &y& Elsevier]

Novel nonlinear optical (NLO) chromophore using benzo[b]furan moiety and trifluoromethyl-substituted tricyanofuran as the electron donor and acceptor respectively was designed and prepared. The structure of the novel chromophore was determined by NMR spectra, and the photophysical properties were studied via UV-vis spectra. The thermal decomposition temperature (T d)value of the obtained NLO chromophore reached to 212 °C, which endow the chromophore with good thermal stability during the materials processing. The nonlinearity of the chromophore was evaluated through theoretical calculation and electro-optic (EO) activity test, and the highest EO coefficient (r 33) was determined to 28 pm/V at the loading density of 25 wt% in polymethyl methacrylate. • Novel benzofuran-based nonlinear optical chromophore was designed and synthesized. • The acceptor was unexpected linked to the β -position of furan in the chromophore. • The present chromophore exhibited go0d thermal stability (T d reached to 212 °C). • The maximum EO coefficient of the reported chromophore reached to 28 p.m./V. [ABSTRACT FROM AUTHOR]

Abstract Novel nonlinear optical chromophores JC-TCF and JC-FTCF using tetramethyljulolidine-based coumarin as the electron-donor and tricyanofuran derivatives as the electron acceptors were designed, synthesized and investigated. The obtained chromophores own good solubility in common solvents, and good compatibility with host polymers. The chromophores also have good thermal stability, and the decomposition temperature exceed 200 °C. The UV–vis spectra indicated that JC-TCF and JC-FTCF possess good intramolecular charge transfer ability. Density functional theory (DFT) was used to study the energy gap and first-order hyperpolarizability(β). After contact poling, the guest-host polymer films of polymethyl methacrylate containing 20% wt JC-TCF and 20% wt JC-FTCF exhibited the highest electro-optic coefficient (r 33) up to 40 p.m./V and 76 p.m./V respectively, and the results indicated the chromophores' microscopic β value could be effectively translated to macroscopic EO activity, and the tetramethyljulolidine-based coumarin could be an useful candidate in the development of NLO materials. Highlights • Julolidine-based coumarin was used as electron-donor in design of NLO materials. • The coumarin's good electron-donation ability obviously enhanced the NLO properties. • The obtained materials exhibited better EO activity compared to the FTC chromophores. • The maximum EO activity of reported NLO chromophores reached to 76 p.m./V. • Coumarin could be an useful candidate in the development of NLO materials. [ABSTRACT FROM AUTHOR]

One novel chromophore C based on 4,4′-bis(diethylamino) benzophenone donor and CF 3 -Ph-TCF acceptor was synthesized. Alkoxy isolation group was introduced also. Cyclic voltammetry measurements showed that the new chromophore C had a much smaller energy gap (ΔE = 1.25 eV) than chromophore A and B. UV–Vis absorption indicated that obvious red shift (more than 100 nm) obtained for chromophore C. The doped film C containing CF 3 -Ph-TCF chromophore showed a r 33 value of 235 pm/V at the concentration of 25 wt% which is much higher than that of the TCF based chromophore A (149 pm/V) and B (163 pm/V). The thermal stability were high enough (>200 °C) to be further fabricated in devices and good EO property make application possible. [ABSTRACT FROM AUTHOR]

Two novel bichromophores YL1 and YL2 based on traditional aniline chromophore YL were synthesized by Cu(I) catalyzed click-reaction and systematically investigated in this paper. The UV–Vis, electrochemical property, thermal stability and EO activity of these chromophores were systematically studied and discussed. These two bichromophores showed good thermal stability. Then nonlinear optical polymer films were fabricated by doping chromophores into polymethylmethacrylate (PMMA). The doped films containing bichromophores YL1 and YL2 showed r 33 values of 20 and 17 p.m./V at concentration of 25 wt% at 1310 nm. These values were respectively 2.85 times and 2.43 times of the EO activity of chromophore YL (7 p.m./V). High r 33 values indicated that the new structure of bichromophores YL1 and YL2 can reduce intermolecular electrostatic interactions, thus enhancing macroscopic EO activity. These properties suggested the potential use of the new bichromophores in nonlinear optical materials. [ABSTRACT FROM AUTHOR]

A series of high performance chromophores P1 P3, based on N -(4-dibutylaminophenyl) tetrahydroquinolinyl or julolidinyl donors, and phenyl-trifluoromethyl-tricyanofuran acceptors linked together via π-conjugation through thiophene or vinylene moieties as the bridges, have been designed and synthesized. Density functional theory (DFT) was used to calculate the HOMO-LUMO energy gaps and first-order hyperpolarizability (β) of these chromophores. Chromophores P1 and P3 had good thermal stabilities with glass transition temperature higher than 110 °C. Most importantly, the high molecular hyperpolarizability of these chromophores can be effectively translated into large electro-optic (EO) coefficients (r 33 ) in poled polymers with rational chromophore designs. In electro-optic activities, the poled films of P1/APC, P2/APC and P3/APC afforded r 33 values of 223, 283 and 278 pmV −1 , respectively, at 1310 nm at the doping concentration of 25 wt%, which showed significant enhancement over the similar EO polymer systems previously reported. [ABSTRACT FROM AUTHOR]

Two series of highly efficient nonlinear optical chromophores A1-C1 and A2-C2 based on the julolidinyl donors and tricyanofuran or phenyl-trifluoromethyl-tricyanofuran acceptors (CF 3 -Ph-TCF) linked together via π-conjugation through thiophene or pyrrole or tetraene moieties as the bridges, have been synthesized and investigated. The ultraviolet absorption, solvatochromic, thermal stabilities and electro-optic activities of these chromophores were systematically studied to illustrate structure-performance relationships within the six chromophores. All the chromophores exhibited good thermal stabilities with the decomposition temperatures (T d ) higher than 200 °C. Appropriate combination of the π-conjugated bridge, electron-donor and electron-acceptor as well as the isolated group in the chromophores plays an important role in achieving larger electro-optic activities. Exemplified by the chromophore A2 with CF 3 -Ph-TCF acceptor, it gave a very large r 33 value of 223 pmV −1 at 1310 nm at the doping concentration of 25 wt%. [ABSTRACT FROM AUTHOR]

A novel chromophore based on N -(4-dibutylaminophenyl)tetrahydroquinolinyl donor group was synthesized to compare with traditional chromophores based on either diethylaminophenyl or triarylaminophenyl donor groups. Cyclic voltammetry measurements showed that the new chromophore had a much smaller energy gap than the structurally related chromophores. Density functional theory calculations suggested that the molecular quadratic hyperpolarizability (μβ) value of tetrahydroquinolinyl chromophore is 65% and 110% larger than that of either the diethylaminophenyl or triarylaminophenyl chromophores, respectively. The doped film containing the tetrahydroquinolinyl chromophore showed an r 33 value of 126 pm/V at the concentration of 25 wt% which is much higher than the electro-optic activity of the diethylaminophenyl derived chromophore (39 pm/V) and six times higher than that of the traditional triarylaminophenyl chromophore (19 pm/V). The tetrahydroquinolinyl chromophore possesses much higher thermal stability (with its onset decomposition temperature above 280 °C) than those of commonly used alkyl chromophores. [ABSTRACT FROM AUTHOR]

Three novel nonlinear optical chromophores based on the same bis( N,N -diethyl)aniline donor have been synthesized and systematically characterized. These chromophores showed good thermal stability and chromophore y1 showed the best thermal stability of 249 °C. Besides, compared with the chromophore (y1) without the substituted group, chromophores y2 and y3 show better intramolecular charge-transfer absorption. Most importantly, the high molecular hyperpolarizability of these chromophores can be effectively translated into large electro-optic coefficients. The electro-optic coefficient of poled films containing 25% wt of chromophores y1–y3 doped in amorphous polycarbonate afforded values of 149, 138 and 157 pm/V at 1310 nm for chromophores y1–y3 respectively. These results indicated that the double donors of bis( N,N -diethyl)aniline unit can efficiently improve the electron-donating ability and the special structure can reduce intermolecular electrostatic interactions, thus enhancing the macroscopic electro-optic activity. These properties, together with good solubility, suggest the potential use of these chromophores as advanced materials. [ABSTRACT FROM AUTHOR]

A series of second-order nonlinear optical chromophores containing an identical π-bridge and electron acceptor but different, aromatic amine electron-donating groups have been synthesized and systematically investigated. The donors studied here include traditional donors carbazole, triphenylamine and N , N -diethylaniline and novel donor phenothiazine, phenoxazine and N -(4-methoxyphenyl)phenoxazine. The ultraviolet absorption, solvatochromic, redox properties, density functional theory calculations, thermal stabilities and electro-optic activities of these chromophores were systematically studied to compare the strength of the donors and illustrate the structure–performance relationships within six chromophores. The results show that the new donors have stronger electron-donating ability than traditional donors. Moreover, they show reduced energy gap, much larger molecular quadratic hyperpolarizability (μβ) and r 33 value. Exemplified by the N -(4-methoxyphenyl)phenoxazine chromophore, it showed nearly three times higher μβ and more than four times higher r 33 value than that of the N -hexylcarbazole containing chromophore. [ABSTRACT FROM AUTHOR]

Two novel chromophores based on the phenoxazine (chromophore L1) or phenothiazine (chromophore L2) donor, and tricyanofuran acceptors linked together via thiophene as the bridges have been synthesized and systematically investigated. Cyclic voltammetry measurements showed that chromophore L1 had smaller energy gap than chromophore L2 due to the stronger electron-donating ability. Moreover, Density functional theory calculations suggested that the β value of chromophore L1 is 17% larger than that of chromophore L2. The doped film containing the chromophore L1 showed an r 33 value of 49 pm/V at the concentration of 25 wt% which is two times higher than the EO activity of the chromophore L2 (23 pm/V) and the traditional aryl chromophore (10–20 pm/V). High r 33 value, high thermal stability (onset decomposition temperatures higher than 220 °C) suggests the potential use of the new chromophore in nonlinear optical materials. [ABSTRACT FROM AUTHOR]