A highly strained macrocycle comprising four[4]helicene panels,[4]cyclo[4]helicenylene([4]CH,1),was synthesized through a one-pot macrocyclization and chemically reduced by alkali metals(Na and K),revealing a four-ele...A highly strained macrocycle comprising four[4]helicene panels,[4]cyclo[4]helicenylene([4]CH,1),was synthesized through a one-pot macrocyclization and chemically reduced by alkali metals(Na and K),revealing a four-electron reduction process.The resulting di-,tri-,and tetraanions of compound 1 were isolated and crystallographically characterized by X-ray diffraction.Owing to the four axially chiral bi[4]helicenyl fragments,a reversible stereo transformation of 1 between the(S,R,S,R)-and(S,S,R,R)-configurations was disclosed upon the twoelectron uptake,which was rationally understood by theoretical calculations.The(S,S,R,R)-configuration of 1^(2-)was further stabilized in triply reduced and tetra-reduced states,where structural deformation led by charges and metal complexation was observed.This study proposed an approach to alter the configuration of cycloarylenes in addition to thermal treatment.展开更多
基金support from the National Natural Science Foundation of China(22301219,22201035)the Fundamental Research Funds for the Central Universities(22120240039,2242023R40024)+4 种基金the Start-up Research Fund of Southeast University(RF1028623055)the Shanghai Synchrotron Radiation Facility(2024-NFPS-PT-501026)JSPS KAKENHI(19H02552)We are grateful to Prof.Hiroyuki Isobe(University of Tokyo)for helpful discussions,and to KEK Photon Factory BL-17A beamline(2023G604 and 2021G589)SPring-8 BL38B1 and BL45XU beamlines(2018B1394 and 2021B1517)for the access to the X-ray diffraction instruments.
文摘A highly strained macrocycle comprising four[4]helicene panels,[4]cyclo[4]helicenylene([4]CH,1),was synthesized through a one-pot macrocyclization and chemically reduced by alkali metals(Na and K),revealing a four-electron reduction process.The resulting di-,tri-,and tetraanions of compound 1 were isolated and crystallographically characterized by X-ray diffraction.Owing to the four axially chiral bi[4]helicenyl fragments,a reversible stereo transformation of 1 between the(S,R,S,R)-and(S,S,R,R)-configurations was disclosed upon the twoelectron uptake,which was rationally understood by theoretical calculations.The(S,S,R,R)-configuration of 1^(2-)was further stabilized in triply reduced and tetra-reduced states,where structural deformation led by charges and metal complexation was observed.This study proposed an approach to alter the configuration of cycloarylenes in addition to thermal treatment.
