The chemical and electrochemical stimuli viologen substituted phthalocyanine with tunable optical features1.

In this study, viologen-tetrasubstituted Zn(II) phthalocyanines ( and ) were designed and synthesized to achieve the tunable optical features via redox-active viologen groups. Several parameters relevant to the evaluation of the tunable optical features have been investigated: UV-Vis, cyclic voltammetry (CV), EPR, square wave voltammetry (SWV), and theoretical analyses. The results showed that upon reductions and oxidations of viologen groups either chemically or electrochemically, the optical features of and change drastically with switchable processes.

Kinetic Barrier to Enzyme Inhibition Is Manipulated by Dynamical Local Interactions in DHFR.

Dihydrofolate reductase (DHFR) is an important drug target and a highly studied model protein for understanding enzyme dynamics. DHFR's crucial role in folate synthesis renders it an ideal candidate to understand protein function and protein evolution mechanisms. In this study, to understand how a newly proposed DHFR inhibitor, 4'-deoxy methyl trimethoprim (4'-DTMP), alters evolutionary trajectories, we studied interactions that lead to its superior performance over that of trimethoprim (TMP).

Engineering supramolecular helical assemblies interplay between carbon(sp) tetrel and halogen bonding interactions.

Building supramolecular helical structures is a challenge due to difficulties in the design and control of competitive noncovalent forces. Herein, we report three scaffolds (1a, 1b, and 1c) decorated with -CN and -Br groups. These groups known for their ability to form multiple noncovalent interactions and with efficient design can be utilized to achieve such complex structures.

Investigation of iron release from the N- and C-lobes of human serum transferrin by quantum chemical calculations.

Human serum transferrin binds ferric ions with high affinity and delivers them into cells receptor-mediated endocytosis upon a decrease in pH in the endosome. Protonation events and conformational changes are known to play an important role in iron-release though the release is not yet fully understood. Human serum transferrin consists of two similar lobes which release iron at different rates.

Theoretical Investigation of the Biogenetic Pathway for Formation of Antibacterial Indole Alkaloids from .

The energetic viability of the previously proposed biogenetic pathway for the formation of two unique monoterpenoid indole alkaloids, voacafricine A and B, which are present in the fruits of , was investigated using density functional theory computations. The results of these calculations indicate that not only is the previously suggested pathway not energetically viable but also that an alternative biosynthetic precursor is likely.

Influence of odd-even effect and intermolecular interactions in 2D molecular layers of bisamide organogelators.

Organogelators have a wide range of use in everyday life including drug delivery and controlled release, surface coating and paper industry. In this study, a series of model bisamides have been analyzed as potential organogelators. These molecules are connected by odd and even numbered methylene units () in length ranging from 2 to 9.

1,3-Dipolar Cycloaddition Reactions of Low-Valent Rhodium and Iridium Complexes with Arylnitrile N-Oxides.

The reactions between low-valent Rh(I) and Ir(I) metal-carbonyl complexes and arylnitrile oxides possess the electronic and structural features of 1,3-dipolar cycloadditions. Density functional theory (DFT) calculations on these reactions, involving both cyclopentadienyl and carboranyl ligands on the metal carbonyl, explain the ease of the chemical processes and the stabilities of the resulting metallaisoxazolin-5-ones. The metal-carbonyl bond has partial double bond character according to the Wiberg index calculated through NBO analysis, and so the reaction can be considered a normal 1,3-dipolar cycloaddition involving M═C bonds.

Computational Studies on Cinchona Alkaloid-Catalyzed Asymmetric Organic Reactions.

Remarkable progress in the area of asymmetric organocatalysis has been achieved in the last decades. Cinchona alkaloids and their derivatives have emerged as powerful organocatalysts owing to their reactivities leading to high enantioselectivities. The widespread usage of cinchona alkaloids has been attributed to their nontoxicity, ease of use, stability, cost effectiveness, recyclability, and practical utilization in industry.

A Theoretical Study of the Mechanism of the Desymmetrization of Cyclic meso-Anhydrides by Chiral Amino Alcohols.

The alcoholysis of cyclic meso-anhydrides catalyzed by β-amino alcohols has been investigated with DFT quantum mechanics to determine the mechanism of this reaction. Both nucleophilic catalysis and general base catalysis pathways are explored for methanol-induced ring opening of an anhydride catalyzed by a chiral amino alcohol. The nucleophilic pathway involves a late transition state with a high energy barrier.