In this brief review, nonlinear optical (NLO) chromophores widely used in electro-optic (EO) devices are summarized according to their EO coefficients. The advances of EO modulators based on organic materials in high bandwidth and low half wave voltages (V_π) are discussed. The review is mainly devoted to the following aspects: (1) verification of high frequency operation and reduction of V_π for all polymer waveguide EO modulators; (2) structures and advantages of sol–gel waveguide EO modulators; (3) principles and developments of silicon–organic hybrid (SOH) EO modulators. All the considerations are illustrated by the architecture of the devices and the used physical and chemical principles are explained in detail. Further means of improvement of their parameters are indicated.

NiS ₂ acts as an active and selective electrocatalyst for the two-electron O ₂ reduction reaction in acids, achieving a selectivity of up to 99% and a H ₂ O ₂ yield rate of 109 ppm h ⁻¹ . The catalytic mechanism is further investigated by theoretical calculations.

Three novel second order nonlinear optical chromophores based on julolidinyl donors and tricyanovinyldihydrofuran (TCF) acceptors linked together via modified pyrrole π-conjugation (chromophores A and B) or thiophene moieties (chromophore C) as the bridges have been synthesized and systematically characterized. In particular, the pyrrole moiety bridge has been modified with the electron withdrawing group (–Br, –NO₂) substituted benzene ring. The introduction of side phenyl groups to chromophores A and B can increase the thermal and chemical stability and reduce dipole–dipole interactions so as to translate their hyperpolarizability (β) values into bulk EO performance more effectively than chromophore C. Moreover, DFT calculations suggested that the additional electron withdrawing groups in chromophores A and B could increase the β value compared to that of chromophore D without substituted phenyl groups, and they showed different influences on the solvatochromic behavior, thermal stability, and electro-optic activity of the chromophores. EO responses (r₃₃ values) of guest–host polymers containing pyrrole-bridged chromophores were reported. Incorporation of chromophores A and B into APC provided large electro-optic coefficients of 86 and 128 pm V⁻¹ at 1310 nm with a high loading of 30 wt%. Film-C/APC containing 25 wt% of chromophore C provides an EO coefficient of 98 pm V⁻¹.

New Y-type chromophores FTC-yh1 and FTC-yh2 containing bis(N,N-diethyl)aniline as a novel electron-donor, thiophene as a π-conjugated bridge and tricyanofuran (TCF) as an acceptor 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 chromophores showed better thermal stability with their decomposition temperatures all above 240 °C. Most importantly, the high molecular hyperpolarizability of these chromophores can be effectively translated into large electro-optic (EO) coefficients (r₃₃) in poled polymers. The doped film-A containing 25 wt% chromophore FTC-yh1 displayed a value of 149 pm V⁻¹ at 1310 nm, and the doped film-B containing FTC-yh2 showed a value of 143 pm V⁻¹ at the concentration of 25 wt%. These values are almost four times higher than the EO activity of usually reported traditional single (N,N-diethyl)aniline nonlinear optical (NLO) chromophores FTC. High r₃₃ values indicated that the double donors of the bis(N,N-diethyl)aniline unit can efficiently improve the electron-donating ability and reduce intermolecular electrostatic interactions, thus enhancing the macroscopic EO activity. These properties, together with the good solubility, suggest the potential use of the new chromophores as advanced material devices.