Synthesis and Optical Property Modulation of Substituted [2.2]Paracylophanes through Through‐Space Conjugation

Abstract

Abstract4,16‐para‐substituted [2.2]paracylophanes with naphthalene (PCP‐NAP), anthracene (PCP‐ANTH), and tetraphenylethylene (PCP‐TPE), as new through‐space conjugated dimers, were prepared by the Suzuki‐Miyaura cross‐coupling reaction of 4,16‐diboryl[2.2]paracyclophane and the corresponding bromo derivative using Pd(PPh3)4 as a catalyst and KOH as a base. The synthesized compounds were fully characterized by NMR and HR‐MS, and their photophysical and electrochemical properties were studied. The photoluminescence quantum yield of PCP‐NAP, PCP‐ANTH were determined to be 0.21, 0.50, and for PCP‐TPE in aggregated state 0.31, respectively. PCP‐TPE exhibited aggregation‐induced emission characteristics when the water fraction was greater than 50 % in THF/water mixtures. PCP‐ANTH and PCP‐TPE were also characterized by X‐ray crystallography, PCP‐ANTH crystallizes in centrosymmetric monoclinic space group C2/c and PCP‐TPE crystallizes in the centrosymmetric triclinic space group P‐1 with one molecule residing at the inversion center. The observed properties of these π‐stacked dimers were compared with respect to through‐space conjugation and conjugation length in the structure.