Strained delta-stacked motifs of nanogridarenes achieved via Pd-PPh3-controlled diastereoselective C-H gridization

Strained nanogrids are the hybrids between nanogrids and nanorings with high strain like CPPs, offering state-of-the-art models and versatile nanobricks for advanced materials. Herein, we reported the unique blue-emitting strained triangle windmill-type nanogrids (TWGs) with π-interrupted backbones and delta-stacked motifs that have two diastereoisomers with different strains (cis-trans-TWG 15.60 kcal/mol, cis-cis-TWG 13.31 kcal/mol). They are synthesized by Pd-PPh3-assisted C-H gridization with size-selectivity of TWGs in 35 % yield and diastereoselectivity of cis-trans-TWG/cis-cis-TWG (80:20). Single-crystal X-ray diffraction and non-covalent index reveal both diastereoisomers exhibit the unique angle, bending, torsion as well as steric strains. Among those, torsion strain of cis-trans-TWG is much greater than that of cis-cis-TWG. Furthermore, strain-induced red shift of 25 nm in cis-trans-TWG than cis-cis-TWG was confirmed by TDDFT and photophysics charaterization. Interestingly, aggregates-induced emission switching and enhancement was observed in cis-trans-TWG skeleton with concentration from 10-5 to 10-1.