Why does the orientation of azulene affect the two-photon activity of a porphyrinoid-azulene system?

Attaching a dipolar molecule in a symmetric system induces a major change in the electronic structure, which may be reflected as the enhancement of the optical and charge-transfer properties of the combined system as compared to the pristine ones. Furthermore, the orientation of the dipolar molecule may also affect the said properties. This idea is explored in this work by taking porphyrinoid molecules as the pristine systems. We attached azulene, a dipolar molecule, at various positions of five porphyrinoid cores and studied the effect on charge-transfer and one- and two-photon absorption properties using the state-of-the-art RICC2 method. The attachment of azulene produces two major effects - firstly it introduces asymmetry in the system and, secondly, being dipolar, it makes the resultant molecule dipolar/quadrupolar. Porphyrin, N-confused porphyrin, sub-porphyrin, sapphyrin, and hexaphyrin are used as core porphyrinoid systems. The change in charge-transfer has been studied using the orbital analysis and charge-transfer distance parameter for the first five singlet states of the systems. The effect of orientation of azulene on the said properties is also explored. The insights gained from our observations are explored further at the dipole and transition dipole moment levels using a three-state model.

Influence of Essential Oil Composition on Antioxidant and Antibacterial Activities of Three Cultivars of Cymbopogon Flexuosus: In Vitro and In Silico Study.

The present study investigates and compares the chemical composition, antioxidant, and antibacterial properties of lemongrass essential oils (LEOs) extracted from fresh leaves of three cultivars of C. flexuosus: Krishna (CF-KA), Cauvery (CF-CA), and Nima (CF-NI), grown in Chhattisgarh plains. Analysis through gas chromatography techniques revealed that citral content was highest in CF-NI (79.82±1.00 %), followed by CF-KA (69.75±2.70 %) and CF-CA (54.75±1.22 %). In vitro antioxidant experiments demonstrated that CF-CA had better scavenging capacity in DPPH (SC50=164.55±9.35 µg/mL) and ABTS (SC50=4.76±0.57 GEAC/g) free radical scavenging assays. The in vitro antibacterial experiments against Staphylococcus aureus (MTCC3160) and Escherichia coli (MTCC1687) demonstrated CF-NI's enhanced antibacterial efficacy with significant inhibition zones and low MIC values. In silico molecular docking results revealed that LEO compounds like caryophyllene oxide, humulene epoxide, ß-caryophyllene etc. have better binding affinities towards targeted protein molecules responsible for bacterial cell mechanisms and production of reactive oxygen species (ROS) compared to their native ligands. Variations in biological activities among cultivars were potentially linked to the proportion of phytoconstituents in their chemical composition.