Vasileios Drogkaris's research while affiliated with Wesleyan University and other places

The nucleophile‐initiated mechanism of thiol‐Michael reactions naturally leads to the formation of undesired nucleophile byproducts. Three aza‐Michael compounds representing nucleophile byproducts of thiol‐acrylate reactions initiated by 4‐dimethylaminopyridine (DMAP), 1‐methylimidazole (MIM), and 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) have been synthesized and their reactivity in the presence of thiolate has been investigated. Spectroscopic analysis shows that each nucleophile byproduct reacts with thiolate to produce a desired thiol‐acrylate product along with liberated aprotic amines DMAP, MIM, or DBU, thus demonstrating that these byproducts are reactive rather than persistent. Density functional theoretical computations support experimental observations and predict that a β‐elimination mechanism is favored for converting each nucleophile byproduct into a desired thiol‐acrylate product, though an SN2 process can be competitive (i. e. within <2.5 kcal/mol) in less polar solvents.

Three increasingly π-conjugated covalent organic polygons have been prepared by the dynamic covalent condensation of catechol-based oligo(phenylene ethynylene) derivatives with phenylenebis(boronic acid). The assemblies represent a series of boronate ester “ladders” wherein two electron rich oligo(phenylene ethynylene) “rungs” are bridged by electron deficient aryl boronate ester “rails,” resulting in quasi-two-dimensional oligomers of increasing size. Spectroscopic and computational investigations suggest that the ladders exhibit a greater effective conjugation length than comparable oligo(phenylene ethynylene) compounds not bridged by aryl boronate esters. Different conformations, substitutions, and constitutions of boronate ester ladders are also modeled to gain further insight into their influence on π-conjugation and HOMO-LUMO gaps of isolated one-dimensional versus bridged, quasi-two-dimensional conjugated organic materials.