Intramolecular Photoinduced Charge Transfer and Recombination Dynamics in Vinylarene Terminated Organosilanes

Disilane-bridged architectures: an emerging class of molecular materials

Disilanes are organosilicon compounds that contain saturated Si-Si bonds. The structural characteristics of Si-Si single bonds resemble those of C-C single bonds, but their electronic structure is more similar to that of C[double bond, length as m-dash]C double bonds, as Si-Si bonds have a higher HOMO energy level. These organosilicon compounds feature unique intramolecular σ electron delocalization, low ionization potentials, polarizable electronic structure, and σ-π interaction. It has been demonstrated that the employment of disilane units (Si-Si) is a versatile and effective approach for finely adjusting the photophysical properties of organic materials in both solution and solid states. In this review, we present and discuss the structure, properties, and relationships of novel σ-π-conjugated hybrid architectures with saturated Si-Si σ bonds. The application of disilane-bridged σ-conjugated compounds as optoelectronic materials, multifunctional solid-state emitters, CPL, and non-linear optical and stimuli-responsive materials is also reviewed.

Charge Transfer and Level Lifetime in Molecular Photon-Absorption upon the Quantum Impedance Lorentz Oscillator

On the strength of the new quantum impedance Lorentz oscillator (QILO) model, a charge-transfer method in molecular photon-absorption is proposed and imaged via the numerical simulations of 1- and 2-photon-absorption (1PA and 2PA) behaviors of the organic compounds LB3 and M4 in this paper. According to the frequencies at the peaks and the full width at half-maximums (FWHMs) of the linear absorptive spectra of the two compounds, we first calculate the effective quantum numbers before and after the electronic transitions. Thus, we obtain the molecular average dipole moments, i.e., 1.8728 × 10^-29 C·m (5.6145 D) for LB3 and 1.9626 × 10^-29 C·m (5.8838 D) for M4 in the ground state in the tetrahydrofuran (THF) solvent. Then, the molecular 2PA cross sections corresponding to wavelength are theoretically inferred and figured out by QILO. As a result, the theoretical cross sections turn out to be in good agreement with the experimental ones. Our results reveal such a charge-transfer image in 1PA near wavelength 425 nm, where an atomic electron of LB3 jumps from the ground-state ellipse orbit with the semimajor axis a_i = 1.2492 × 10^-10m = 1.2492 Å and semiminor axis b_i = 0.4363 Å to the excited-state circle (a_j = b_j = 2.5399 Å). In addition, during its 2PA process, the same transitional electron in the ground state is excited to the elliptic orbit with a_j = 2.5399 Å and b_j =1.3808 Å, in which the molecular dipole moment reaches as high as 3.4109 × 10^-29 C·m (10.2256 D). In addition, we obtain a level-lifetime formula with the microparticle collision idea of thermal motion, which indicates that the level lifetime is proportional (not inverse) to the damping coefficient or FWHM of an absorptive spectrum. The lifetimes of the two compounds at some excited states are calculated and presented. This formula may be used as an experimental method to verify 1PA and 2PA transition selection rules. The QILO model exhibits the advantage of simplifying the calculation complexity and reducing the high cost associated with the first principle in dealing with quantum properties of optoelectronic materials.

Highly selective addition of cyclosilanes to alkynes enabling new conjugated materials

Hybrid σ,π-conjugated cyclosilanes were synthesized via highly selective hydrosilylation and have shown great potentials as building blocks to construct novel conjugated polymers with control of tacticity.