Control of H- and J-aggregate formation via host-guest complexation using cucurbituril hosts

Suresh Gadde; Elizabeth K Batchelor; Joshua P Weiss; Yonghua Ling; Angel E Kaifer

doi:10.1021/ja807197c

Control of H- and J-aggregate formation via host-guest complexation using cucurbituril hosts

J Am Chem Soc. 2008 Dec 17;130(50):17114-9. doi: 10.1021/ja807197c.

Authors

Suresh Gadde¹, Elizabeth K Batchelor, Joshua P Weiss, Yonghua Ling, Angel E Kaifer

Affiliation

¹ Department of Chemistry and Center for Supramolecular Science, University of Miami, Coral Gables, Florida 33124-0431, USA.

PMID: 19007116
DOI: 10.1021/ja807197c

Abstract

The binding interactions between two cyanine dyes, pseudoisocyanine (PIC) and pinacyanol (PIN), and the cucurbit[n]uril hosts, cucurbit[7]uril (CB7) and cucurbit[6]uril (CB6), were investigated by electronic absorption spectroscopy and DFT computational methods. The CB7 host forms more stable complexes with both dyes than CB6 and the computational studies suggest that the cavity of the smaller host CB6 is not threaded by the dyes. The equilibrium association constants (K) for complexation by CB7 were measured and found to be 2.05 x 10(4) and 3.84 x 10(5) M(-1) for PIC and PIN, respectively, in aqueous media at 23 degrees C. CB7 complexation was found to effectively disrupt the intermolecular forces responsible for the aggregation of both dyes. Thus, CB7 completely disrupts the J-aggregates formed by PIC and the H-aggregates (as well as lower concentrations of J-aggregates) formed by PIN. In both cases a competing guest, 1-aminoadamantane (AD), could be used to adjust the extent of aggregation of the cyanine dye. AD regulates aggregate formation because it forms an extremely stable complex with CB7 (K approximately = 10(12) M(-1)) and exerts a tight control on the CB7 concentration available to interact and bind with the dye.