Synthesis and Optical Property Modulation of Substituted [2,2]-paracylophanes through Through-Space Conjugation

4,16-para-substituted [2,2] paracylophane with naphthalene (PCP⎼NAP), anthracene (PCP⎼ANTH), and tetraphenylethylene (PCP⎼TPE) as a new through-space conjugated dimers were prepared by the Suzuki–Miyaura cross-coupling reaction of 4,16-diboryl [2,2] paracyclophane and respective bromo derivative using Pd(PPh3)4 as a catalyst and KOH as a base. The synthesized compounds were fully characterized by NMR, HR-MS and their photophysical, and electrochemical properties were studied. The quantum yield of PCP⎼NAP, PCP⎼ANTH and PCP-TPE were calculated and estimated as 0.21, 0.50 and 0.31 respectively. PCP⎼TPE exhibited aggregation-induced emission characteristics when the water fraction was higher than 50% in the THF/water mixtures. PCP-ANTH and PCP-TPE were also characterized by X-ray Crystallography, obtained single crystal of PCP-ANTH crystalizes in centrosymmetric monoclinic space group C2/c. A single crystal of PCP-TPE crystallizes in the centrosymmetric triclinic space group P⎼1 with one molecule residing on the inversion centre. The observed properties of these π-stacked dimers were compared through through-space Conjugation and conjugation length in the structure.