Science Seminars

Click Porphyrins: Hosts for Chiral and Non-Chiral Guests

This seminar presents Dr. Starnes’ research efforts in porphyrin-related host-guest chemistry including his post-doctoral work on porphyrin-cavitand hybrids, work conducted at New Mexico State University on anion receptors derived from beta-functionalized porphyrins; primarily, the seminar describes his most recent work at Texas A&M-Commerce, which centers on meso-functionalized porphyrins for the development of anion and amine guests. The synthesis of 15 non-chiral porphyrin hosts and over 25 chiral porphyrin hosts and their recognition properties with non-chiral and chiral guests that vary in geometry and functionality is described. For the creation of the chiral hosts, a porphyrin isocyanate was reacted with a variety of commercially available chiral amines and chiral amino alcohols; thus, the chiral hosts presented are practically ‘off the shelf’ receptors that are available in diversity in high yield with minimal synthetic effort. The porphyrin hosts are functionalized at one meso position with guest binding sites that work in tune with the porphyrin metal center to create a binding pocket for guests. Thus, a key aspect of the work centers on the design of the receptors with recognition elements that are pre-positioned to mimic the geometry and functionality of the target guest. The results show that the metal binding interaction and the guest shape-complementarity of the hosts are key components to the porphyrin hosts ability to bind guests selectivity. Several hosts display a conformationally-induced organization upon binding to guests.