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Two principally novel chromophores A, B based on fluorene electron donor were synthesized and explored by 1H NMR, 13C NMR, and MS spectra. The delocalized energy levels have been estimated by UV–Vis absorption spectra. The principal innovation consists in modification by addition of amino group. The titled materials have demonstrated a high solubility in common organic solvents, good compatibility with polymers. The maximally achieved electro-optic efficiency of the poled film possessing 25 wt% of A doped in PMMA (25 wt% A/PMMA) achieved a value of 18 pm/V at wavelength 1310 nm, and 25 wt% B/PMMA possessed an electrooptical coefficient equal to 43 pm/V. This one open a perspective of their direct application in optoelectronic telecommunication devices for laser light modulation. [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]

Due to the simple preparation technology and appropriate crosslinking process, polyurethane was selected as the host polymer for the preparation of organic electro-optics (EO) materials. The synthesis and crosslinking process of polyurethane demanded the nonlinear optical (NLO) chromophore possessing strong stability in acid environment. Fortunately, after the introduction of azo group in the electronic bridge, the stability of this kind of chromophores in acidic environment was improved greatly. Polyurethane EO polymers and EO films based on this kind of chromophore were prepared successfully. The crosslinking process was monitored by infrared spectroscopy clearly. The crosslinking process has direct relationship with the molecular weight of the crosslinkers. Crosslinker of triethanolamine with small molecular weight showed low crosslinking temperature (80 °C) and short crosslinking time (20 min). The crosslinking temperature and time was improved to 140 °C and 60 min based on Poly(bisphenol A glycidyl ether aniline) (BPAN) crosslinker with large molecular weight. More importantly, this kind of EO polymers showed us large second order nonlinear optical coefficients (76.1 pm/V) and good long term stability (130 °C). [ABSTRACT FROM AUTHOR]

Five polymer dispersed liquid crystal films were prepared using 1,1′-binaphthyl–2,2′-diol as the chiral additive with different concentration. These liquid crystal films showed us different electro-optical (EO) properties. Through theoretical analysis and discussion, the relationship between the electro-optical properties and the concentration of 1,1′-binaphthyl–2,2′-diol chiral additive was revealed. As the concentration of the chiral additive increasing, the mesh size of the liquid crystals would become smaller; so the liquid crystal molecules would become harder to be oriented in the electric field and therefore, the threshold voltage and saturation voltage would increase; the open state response times were also extended; the off state response times would be reduced. [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]

Polymers based on N-phenyl maleimide, N-4-propargyl methoxy phenyl maleimide and methyl methacrylate was synthesized. High glass temperatures 183, 179, 159 °C respectively for P 1 , P 2 and P 3 were achieved. EO polymer P 3 –C 1 , P 3 –C 2 and P 3 –C 3 with about 30 wt% chromophore loading density were prepared by attaching Chromophore C 1 , C 2 and C 3 to polymer P 3 using copper-catalyzed Huisgen cycloaddition reactions in mild reaction conditions and high yield. Among the EO polymers, P 3 –C 3 showed us the best solubility in normal solvents and suitable glass temperature. EO films based on EO polymer P 3 –C 3 showed us large EO coefficient of 50 pm/V @1310 nm and good long-term stability, 85% EO activity was kept after annealing at 85 °C for 200 h. [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]

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]

Two novel soluble polyarylates with different nonlinear optical chromophores as the side chains were prepared and characterized by UV-visible spectra, nuclear magnetic resonance, and infrared spectroscopy. The titled polymers show us good thermal stability; the thermal decomposition temperature values were 201 and 253 °C, respectively, for polymer sPAR-CTCF and sPAR-CTCP. The glass transition temperatures were 139 and 122 °C for sPAR-CTCF and sPAR-CTCP, respectively. Chromophore FTC-wl was doped in these polymers as a guest chromophore to form binary chromophore electro-optic (EO) system. And super large EO coefficients (124 pm/V) were found from FTC-wl-doped sPAR-CTCP binary chromophore system at high chromophore loading density. [ABSTRACT FROM AUTHOR]

A tricyanopyrroline chromophore with methacrylate reactive group was synthesized to fabricate the side chain (polymer 1) and crosslinkable (polymer 2) EO (electro optic) polymers with enhanced electrooptical tensor coefficients. These type of polymers have demonstrated the large EO coefficients with values of 29 pm/V and 25 pm/V at wavelength 1,310 nm, respectively. Compared with polymer 1, t polymer 2 had demonstrated a better stability of polar structure. The thermal stability of polar structure was improved for about 100 °C. The temperatures of poling and crosslinking processes were compatible in polymer 2, which allowed obtaining the EO films with improved features. The experimental results have been interpreted with the aid of quantum-chemical calculations. [ABSTRACT FROM AUTHOR]

Organic electro-optic (EO) materials have been widely studied and used in microwave photonic devices, due to their advantages in half-wave voltage, bandwidth, low cost and ease of integration. Nonlinear optical (NLO) chromophores, as the core of organic EO materials, can directly decide the characters of organic EO materials, including large EO activity, long term stability, solubility and optical loss. Auxiliary donors have attracted great attentions in NLO chromophores for their strong electron donating ability and significant isolation effect. This feature article describes the application of auxiliary donor in NLO chromophores, including the EO activities, optical characters, stability, crystal structures and machinability. [ABSTRACT FROM AUTHOR]

Dual D-Pi-A nunchaku-like structure chromophore was designed and synthesized to improve electro-optic (EO) materials׳ EO coefficients ( r 33 ) and long term stability by a simple doping system. The r 33 values of poled APC/10% DIMER1 and APC/20% DIMER1 are 23 pm/V and 45 pm/V respectively. After annealed at 85 °C for 500 h, the poled film of APC/20% DIMER1 can retain more than 85% of its initial r 33 value. All these characters showed us superior prospects of application in EO devices. Chromophore DIMER1 also showed us good thermal stability; its decomposition temperature (Td) was higher than 280 °C, which is enough for its application in the EO devices. Also chromophore DIMER1 had good solubility in amorphous polycarbonate (APC); it could be dissolved in APC at high loading density (25%). [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]

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]

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]

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]

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]

Abstract: A series of novel second-order nonlinear optical chromophores containing additional heteroatoms in donor moieties has been synthesized and systematically characterized. The resulting nonlinear optical chromophores exhibited both good thermal stability (the decomposition temperature in the range of 249 °C–275 °C) and good solubility in common organic solvents such as chloroform, acetone and N, N-dimethyl formamide. In order to investigate the influence of additional heteroatom on the electro-optic activities, UV–Vis spectra and density functional theory calculations were carried out. The results revealed that the donor derived from m-phenylenediamine had higher electron density compared with other three donors. As to electro-optic activities, the doped polymer film-C displayed the highest electro-optic coefficient value of 31 pm/v at the doping concentration of 20 wt%. All these results indicated that the nonlinear optical activities could be enhanced by introducing suitable additional heteroatoms into donor moiety. [Copyright &y& Elsevier]

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]