Intramolecular charge transfer-based linear and nonlinear optical properties of a D–π–A–π–D type organic chromophore: Experimental and computational approach

In the sight of the present demand of scientific exploration in nonlinear optics (NLO), we synthesized a symmetric donor–[Formula: see text]–acceptor–[Formula: see text]–donor (D–[Formula: see text]–A–[Formula: see text]–D) type organic chromophore [2-[2,6-di((E)-styryl)]-4H-pyran-4-ylidene]malononitrile (M1) for linear and nonlinear optical studies. The structural character of the compound M1 was confirmed using 1H NMR, [Formula: see text]C NMR, and IR spectroscopy. The intramolecular charge transfer (ICT) in molecule M1 has been analyzed using absorption and fluorescence spectrometry in different nonpolar and polar solvents. The optical bandgap, optical conductivity, and linear refractive index of M1 were also calculated using UV–Vis absorption spectrum in CHCl3. The thermogravimetric analysis (TGA) was also carried out to check the thermal stability of the compound M1 and it was found to be thermally stable up to 200∘C. Furthermore, the third-order optical nonlinearity in M1 has been investigated elaborately using the [Formula: see text]-scan technique with a continuous wave (CW) diode laser at 520[Formula: see text]nm. The nonlinear absorption ([Formula: see text]), nonlinear refraction ([Formula: see text]), and nonlinear optical susceptibility ([Formula: see text]) were computed for various solution concentrations as well as several laser powers and the magnitude of all the parameters were found to vary linearly with concentration and power. The magnitude of two-photon absorption cross-section ([Formula: see text]) was also calculated and found to be of the order of 10[Formula: see text] GM. The optical limiting performance of the compound was also studied in different solution concentrations using the same laser. Furthermore, DFT and TD-DFT theoretical calculations were performed for the support of experimental results.

Sub-7-femtosecond conical-intersection dynamics probed at the carbon K-edge

Conical intersections allow electronically excited molecules to return to their electronic ground state. Here, we observe the fastest electronic relaxation dynamics measured to date by extending attosecond transient-absorption spectroscopy (ATAS) to the carbon K-edge. We selectively launch wave packets in the two lowest electronic states (D0 and D1) of C2H4+. The electronic D1 → D0 relaxation takes place with a short time constant of 6.8 ± 0.2 femtoseconds. The electronic-state switching is directly visualized in ATAS owing to a spectral separation of the D1 and D0 bands caused by electron correlation. Multidimensional structural dynamics of the molecule are simultaneously observed. Our results demonstrate the capability to resolve the fastest electronic and structural dynamics in the broad class of organic molecules. They show that electronic relaxation in the prototypical organic chromophore can take place within less than a single vibrational period.

Enhanced fluorescence by increasing dimensionality: a novel three-dimensional luminescent metal–organic framework with rigidified ligands

A novel 3D luminescent MOF has been developed by the incorporation of an organic chromophore, demonstrating the photoluminescence of MOFs can be greatly enhanced by increasing their structural dimensionality.

A diketopyrrolopyrrole dye-based dyad on a porous TiO2 photoanode for solar-driven water oxidation

Construction of a water oxidising photoanode with an organic chromophore-catalyst dyad.

An organic chromophore -modified samarium-containing polyoxometalate: excitation-dependent color tunable behavior from the organic chromophores to the lanthanide ion

An organic–inorganic hybrid Ln-POM display reversible color-tunable photoluminescence properties based on excitation from 260 nm to 350 nm, emitting color from blue to pink.

Visible-light photooxidation in water by 1O2-generating supramolecular hydrogels

An aqueous photocatalytic system exploits photophysical properties arising from the formation of supramolecular hydrogels, with properties and assembly modulated by the amino acids appended to an organic chromophore.