Upcoming MDI Seminars

Professor Mamoun M. Bader

Sustainable Chemistry and Materials Laboratory, Alfaisal University
Monday, August 10, 2026 | 11:00 am ET | Brown 6 Seminar Room

Enforcing Planarity and Promoting π-Stacking in π-Conjugated Materials through Molecular Design and Crystal Engineering 

This talk presents two complementary strategies for controlling planarity and π-stacking in π-conjugated organic semiconductors: (i) conformational engineering via intramolecular noncovalent interactions and (ii) structural engineering through rigid fused ladder architectures. Together, these approaches provide general design principles for tuning molecular conformation, electronic structure, and solid-state organization. 

Single-crystal X-ray diffraction reveals that intramolecular N···S contacts in tricyanovinyl (TCV)- and dicyanovinyl (DCV)-functionalized oligothiophenes and ethylenedioxythiophene (EDOT) derivatives act as effective conformational locks, enforcing near-planar geometries and stabilizing, in selected cases, rare syn conformations. In contrast, fused phenoxazine and phenothiazine ladder oligomers eliminate conformational flexibility through covalent ring fusion, producing intrinsically rigid frameworks with efficient π-stacking motifs and intermolecular separations of 3.2–3.4 Å. 

These complementary strategies demonstrate how molecular design and crystal engineering jointly govern structure–property relationships in π-conjugated materials. The results provide transferable design rules for next-generation organic semiconductors for optoelectronic and energy-related applications.