Mechanisms of glycine formation in cold interstellar media: a theoretical study.

The possibility of the formation of glycine (Gly) from fundamental gas molecules in cold interstellar media was studied using quantum chemical methods, transition state theory and microcanonical molecular dynamics simulations with surface hopping dynamics (NVE-MDSH). This theoretical study emphasized five photochemical pathways in the lowest singlet-excited ( ) state, thermochemical processes after non-radiative → relaxations, and photo-to-thermal energy conversion in the NVE ensemble. The optimized reaction pathways suggested that to generate a reactive singlet dihydroxy carbene (HOCOH) intermediate, photochemical pathways involving the HO…CO van der Waals and HO-OC hydrogen bond precursors (Ch (1)_Step (1)) possess considerably lower energy barriers than the state pathways.

Photoluminescence mechanisms of BF-formazanate dye sensitizers: a theoretical study.

Photodynamic therapy (PDT) is an alternative, minimally invasive treatment for human diseases such as cancer. PDT uses a photosensitizer to transfer photon energy directly to cellular O to generate O (Type II), the toxicity of which leads to cancer cell death. In this work, the photoluminescence mechanisms of a BF-formazanate dye sensitizer (BF-FORM) and its iodinated derivative (BF-FORM-D) were studied using complementary theoretical approaches; the photoluminescence pathways in the S and T states were studied using density functional theory (DFT) and time-dependent (TD)-DFT methods, the kinetic and thermodynamic properties of the pathways using the transition state theory (TST), and the time evolution and dynamics of key processes using non-adiabatic microcanonical molecular dynamics simulations with surface-hopping dynamics (NVE-MDSH).

Mechanisms of photoisomerization of the prenylated flavin mononucleotide cofactor: a theoretical study.

The enzymatic decarboxylation of α,β-unsaturated acids using the ferulic acid decarboxylase (Fdc1) enzyme and prenylated flavin mononucleotide (prFMN) cofactor is a potential, environmentally friendly reaction for the biosynthesis of styrene and its derivatives. However, experiments showed that the enzyme activity of Fdc1 depends on the ring structure of prFMN, namely, the iminium and ketimine forms, and the loss of enzyme activity results from prFMN → prFMN photoisomerization. To obtain insight into this photochemical process and to improve the enzyme efficiency of Fdc1, two proposed photoisomerization mechanisms with different proton sources for the acid-base reaction were studied herein using theoretical methods.

Heavy Atom Effect on the Intersystem Crossing of a Boron Difluoride Formazanate Complex-Based Photosensitizer: Experimental and Theoretical Studies.

Photodynamic therapy (PDT) is a photochemical-based treatment approach that involves using light to activate photosensitizers (PSs). Attractively, PDT is one of the alternative cancer treatments due to its noninvasive technique. By utilizing the heavy atom effect, this work modified a class of formazan dyes to improve intersystem crossing (ISC) to improve reactive oxygen species (ROS) generation for PDT treatment.

Near-Infrared Fluorescent pH Responsive Probe for Targeted Photodynamic Cancer Therapy.

We developed a pH dependent amino heptamethine cyanine based theranostic probe (I-IR783-Mpip) that can be activated by near infrared light. I-IR783-Mpip, in acidic condition, exhibited an intense, broad NIR absorption band (820-950 nm) with high singlet oxygen generation upon exposure to NIR light (~850 nm). Theoretical calculations showed that the protonation of the probe in an acidic environment decreased the molecular orbital energy gaps and increased the intramolecular charge transfer efficiency.