The non-adiabatic nanoreactor: towards the automated discovery of photochemistry.

The nanoreactor has previously been introduced to automate reaction discovery for ground state chemistry. In this work, we present the nonadiabatic nanoreactor, an analogous framework for excited state reaction discovery. We automate the study of nonadiabatic decay mechanisms of molecules by probing the intersection seam between adiabatic electronic states with hyper-real metadynamics, sampling the branching plane for relevant conical intersections, and performing seam-constrained path searches.

Experimental and Theoretical Characterization of Ultrafast Water-Soluble Photochromic Photoacids.

UV-visible transient absorption spectroscopy and quantum mechanical simulations are combined to elucidate the photochemical mechanism of two metastable merocyanine/spiropyran photoacids, 2-[()-2-(2-hydroxyphenyl)ethenyl]-3,3-dimethyl-1-(3-sulfopropyl)-3-indol-1-ium (phenylhydroxy-MCH) and 2-[()-2-(1-indazol-7-yl)ethenyl]-3-(3-sulfopropyl)-1,3-benzothiazol-3-ium (indazole-MCH). Transient absorption spectra demonstrate that -acid isomerization to the form results in deprotonation on a picosecond time scale. Ring closure to form spiropyran follows promptly from the appropriate conformation or follows at longer time delays (≫3.

The Mechanics of the Bicycle Pedal Photoisomerization in Crystalline -1,4-Diphenyl-1,3-butadiene.

Direct irradiation of crystalline -1,4-diphenyl-1,3-butadiene (cc-DPB) forms -1,4-diphenyl-1,3,-butadiene via a concerted two-bond isomerization called the bicycle pedal (BP) mechanism. However, little is known about photoisomerization pathways in the solid state and there has been much debate surrounding the interpretation of volume-conserving isomerization mechanisms. The bicycle pedal photoisomerization is investigated using the quantum mechanics/molecular mechanics complete active space self-consistent field/Amber force-field method.