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Principally novel crosslinking nonlinear optical and optoelectronics system based on Diels-Alder reaction was designed. The copolymer of methyl methacrylate and anthracen-9-ylmethyl methacrylate (PMMA-AMA) was used as a host polymer; chromophore ETO was used as guest chromophore; chromophore ETO and N,N-(methylenediphenyl)bismaleimide were used as crosslinker. The thermodynamic property of crosslinking system studied by differential scanning calorimeter (DSC) showed us that the glass transition temperature was about 65 °C and the crosslinking temperature was varied between 80 and 120 °C The crosslinking reactive speed and effectiveness were studied by ultraviolet absorption and infrared absorption spectroscopy with spectral resoluiotn 1 cm. These results have indicated that the cross linking process could be finished at 110 °C for 20 min. Surprisingly, such EO polymer showed us a large EO coefficient of about 96.3 pm/V at wavelength 1 µm and excellent long term stability about 85% with respect to its initial value and can be kept after 250 h of heating at 80 °C. [ABSTRACT FROM AUTHOR]

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]

Organic electro-optic (EO) materials have been widely explored and used in the fabrication of microwave photonic devices. Their principal advantages are the follows: lower half-wave voltage, wider bandwidth, lower cost and more convenience of integration. Organic second order nonlinear optical (NLO) chromophores, as the core of the organic EO devices, define the key technological parameters: EO efficiency, long term stability, solubility and optical losses. In the present review article, the use of D–π–A chromophore molecules with polycyclic electron donors based on julolidinyl structure is reported and discussed. Significant improvement of electron donating ability and appropriate isolated effect are shown. Future perspectives of the application of such kind of NLO chromophores are considered. [ABSTRACT FROM AUTHOR]

Abstract: Two novel nonlinear optical (NLO) chromophores with 4-hydroxycarbazole as the electron donor were successfully designed and synthesized. The 4-hydroxycarbazole had two reaction sites where the isolated groups were introduced to the chromophores. The prepared chromophores were characterized by MS, 1H NMR and UV–vis spectra. Poled films of the chromophores doped in APC afforded the maximum electro-optic (EO) coefficient (r 33) of 40pm/V at 1310nm. This result was better than the similar chromophores reported using carbazole and aniline derivates as electron donor, which indicated that the introduction of isolated groups suppressed the dipole–dipole interaction between chromophores effectively and could aid the alignment of chromophores and improve the EO activity. This had been further demonstrated by the crystal structure analysis. [Copyright &y& Elsevier]

New tricyanopyrroline (TCP) chromophores with rigid-flexible dendron were prepared for second-order nonlinear optical (NLO) application. The chromophores were fully characterized using ultraviolet-visible spectroscopy, nuclear magnetic resonance spectroscopy and mass spectrometry. Thermal gravimetric analysis (TGA) revealed that the chromophores had excellent thermal stability. Large λ and high solvate chromic effects revealed that the chromophores had large second-order optical nonlinearity. The electro-optic coefficients ( r) were measured in the chromophores-doped poly(bisphenol A carbonate) films at the fundamental wavelength of 1310 nm, and the highest γ achieved was 217 pmV. Copyright © 2010 John Wiley & Sons, Ltd. Modification of the TCP chromophore with bulky groups provides reduction of dipole-dipole interactions, thus great improvement of the macroscopic electro-optic (EO) response was achieved by incorporating these chromophores as a guest into amorphous polycarbonate (APC). Furthermore, the modificated chromophore possesses good processability and exhibits high thermal decomposition temperature. [ABSTRACT FROM AUTHOR]

Compared with traditional inorganic second-order nonlinear optical (NLO) materials, organic second-order NLO materials have many advantages in bandwidth, dielectric constant, half-wave voltage, electro-optic (EO) coefficients, processability, and material cost. Due to their potential applications in telecommunications, computing, detection, terahertz generation, and construction of functional photonic crystals, organic NLO materials have been widely studied for several decades. Currently, the poling efficiency and long-term stability are the largest obstacles for the application of organic NLO materials. At the molecular level, these problems are mainly caused by the strong dipole–dipole intermolecular interactions between the NLO chromophores with D-π-A structures. In the molecular design of the polymer system, modification of the chromophores is considered to be an efficient pathway to solve this problem. Since 2009, many studies have been performed by our group to reduce the strong dipole–dipole intermolecular interactions between the chromophores. In this review, the development of organic NLO materials in recent years is summarized, including the following: 1) a brief introduction of organic second-order NLO materials, 2) the requirements of NLO materials for applications in devices, 3) optimization of the first-order hyperpolarizability of NLO chromophores, 4) the optimization of the chromophore loading parameters (N, ), and 5) improvements of the stabilities of organic NLO materials. • Organic second order NLO materials was briefly introduced. • Requirements of NLO materials for applications in devices were discussed. • Optimized method for first-order hyperpolarizability and loading parameters of chromophore were discussed. • Method for improving stability of organic NLO materials was included. [ABSTRACT FROM AUTHOR]

Abstract: Novel NLO chromophore with 3, 5-bis(trifluoromethyl) benzoyl as the isolated group in electron bridge was prepared for investigating the NLO character. Chromophore FTC-wl was characterized using UV–Visible spectra, nuclear magnetic resonance, and mass spectrometry and showed us excellent thermal stability. EO films prepared by poly(bisphenol A carbonate) polymer doped with this chromophore at different content had been poled to afford the highest electro optic coefficients (r33) of 28pm/V. [Copyright &y& Elsevier]

Novel nonlinear optical (NLO) chromophore based on 6-(pyrrolidin-1-yl)-1H-indole as the electron donor group was designed and synthesized. The molecular structure of this chromophore was characterized by 1 H NMR spectra, 13 C NMR spectra, and MS spectra. The delocalized energy level was estimated by UV–Vis. spectra. The thermal property was studied by thermogravimetric analysis (TGA). The poled films containing chromophores ZML-1 with a loading density of 10 wt% in amorphous polycarbonate (APC) afford an average electro-optic (EO) coefficient ( r 33 ) of 19 pm/V at 1310 nm. Compared to the reported aniline-based chromophore ( r 33 = 12 pm/V) analogues, chromophore ZML-1 exhibits enhanced electro-optical activity. [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]

Abstract: Electro-optic (E-O) materials containing methacrylate-co-(methacrylate)propyl(triethoxy)silicane and chromophore FVB were prepared via sol-gel approach. The chromophore FVB was synthesized using microwave-assisted method. The cross-linkable E-O material exhibited excellent film quality, thermal stability and good E-O activity. The highest E-O coefficient value (r 33 ) 39.8pm/V and improved E-O stability was obtained in the copolymer with higher crosslink degree. The E-O stability was much better than other guest-host polymers at room temperature. The results of the E-O coefficients and thermal properties indicated that this kind of copolymer could not only effectively improve the stability but also increase the r 33 values. [Copyright &y& Elsevier]

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]

Abstracts In this work, a series of novel second order nonlinear optical chromophores modified by heteroatom-groups in electron-donor has been synthesized and systematically investigated. The resulting nonlinear optical chromophores exhibited both good thermal stability and good solubility in common organic solvents. UV–Vis spectra and density functional theory calculations were carried out to investigate the influence of heteroatom-groups on the electro-optic activities. The results revealed that increasing the electron-donor strength will not always improve the nonlinear optical activity of chromophore. There is a best match for electron-donor and acceptor. As to electro-optic activities, the doped polymer film- d3 displayed the highest electro-optic coefficient value of 37 pm/v at the doping concentration of 25 wt%. These results indicated that the nonlinear optical activities could be enhanced by finding the best match for electron-donor and acceptor in chromophore design. [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]

Fluorine was non-conjugatedly linked to the donor of nonlinear optical chromophore to investigate the effect of highly electronegative fluorine on intramolecular charge-transfer and electro-optic activities. 1 HNMR spectra and UV–vis absorption were used to investigate that introduction of fluorine change the dielectric environment of intramolecular charge-transfer. Fluorinated chromophore showed more intensified absorption and its absorption properties was more stable to dielectric change in solution. In solid state of guest-host electro-optic polymer films, this dielectric environment stabilization was revealed to attenuate the dipole–dipole interactions of chromophores. Higher electro-optic coefficients (148 pm/V) and higher chromophore loading density (30 wt%) of fluorinated material chr-2/APC than benchmark material chr-1/APC (116 pm/V at 25 wt%) was achieved. [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]

A novel nonlinear optical chromophore with rigid 3-bromo-thiophene (denoted as BTC) as a site-isolation group to suppress the dipole-dipole interaction, was designed and synthesized. UV–vis absorption indicated that BTC showed intensified absorption and large bathochromic solvatochromism. The electro-optic performance studies displayed a highest r 33 value (93 pm/V) at high chromophore loading density of 45%, which indicated that the dipole-dipole interactions were effectively suppressed. The Crystal analysis further demonstrated that the face-to-face antiparallel packing with a long distance of 7.388 Ǻ between the neighboring chromophores was observed. This weak packing interactions suggested that BTC chromophores can be well isolated in electro-optic materials for chromophores’ high efficient alignment. The excellent electro-optic performances endowed BTC potential application in the high-performance electro-optic materials. [ABSTRACT FROM AUTHOR]

Two series of novel electro-optic (EO) polycarbonates incorporating two kinds of tricyanopyrroline-based nonlinear optical (NLO) chromophores were designed and synthesized. These new polycarbonates were prepared through the facile copolymerization of diol NLO chromophores and bisphenol A bis(chloroformate), and the successful preparations were demonstrated by 1H NMR and Fourier transform infrared (FT-IR) spectra. These polycarbonates possessed good thermal stabilities and also showed higher glass transition temperatures (T g) in the range of 156–165 °C. After corona poling, the EO coefficients (r 33) of two poled polycarbonates films were up to 52 pm/V (PC-DTCPC-Ph-2) and 46 pm/V (PC-DTCPC-FPh-2) at the wavelength of 1310 nm. The higher T gs endow the polycarbonates' poled films with good temporal stability of poling-induced dipole alignment, and the resulting poled films of PC-DTCPC-Ph-2 and PC-DTCPC-FPh-2 could retain 95% and 93% of the initial EO activities at 85 °C for more than 500 h respectively. [ABSTRACT FROM AUTHOR]

One novel second order nonlinear optical chromophore based on benzoxazin donor and tricyanovinyldihydrofuran acceptor linked together via thiophene bridge has been synthesized and characterized. According to cyclic voltammetry measurement, chromophore Z showed low energy gap. In addition, chromophore Z displayed good thermal stability with the onset decomposition temperature over 221 °C. The electro-optic coefficient of a poled film containing 25 wt% of chromophore Z doped in polymethylmethacrylate afforded a value of 64 pm/V at 1310 nm. The result showed that chromophore Z , which had good thermal stability and high r 33 values after poling in films, was a promising candidate for practical use. [ABSTRACT FROM AUTHOR]

• A new chromophore was investigated. • Double-donor structure was introduced. • The new structure chromophore showed good nonlinear optical properties. Organic dyes have received extensive attention due to their broad applications related to nonlinear optics, biological and chemical sensors. Herein, a novel chromophore based on double donors and tricyanofuran acceptor was prepared and studied. This new chromophore displayed excellent thermal stability showing the onset decomposition temperature higher than 230 °C. Moreover, density functional theory calculation shows that chromophore y1 presented a lower HOMO-LUMO energy gap and a much larger hyperpolarizability (β) than the single donor chromophore. These results showed that the double donors can increase the donor ability and thus enhance nonlinear optical properties. [ABSTRACT FROM AUTHOR]