TY - JOUR
T1 - 2,7-Dicyanomethylenecarbazole Based Biradicaloid and Corresponding Cyclophane Tetramer: Dynamic Interconversion Controlled by External Stimuli
AU - Wang, Deliang
AU - Capel Ferron, Cristina
AU - Li, Jie
AU - Gamez-Valenzuela, Sergio
AU - Ponce Ortiz, Rocio
AU - Lopez Navarrete, Juan T
AU - Hernandez Jolin, Victor
AU - Yang, Xiaodi
AU - Pena Alvarez, Miriam
AU - Garcia Baonza, Valentin
AU - Hartl, Frantisek
AU - Ruiz Delgado, M Carmen
AU - Li, Hongxiang
PY - 2017/10/4
Y1 - 2017/10/4
N2 - This work reports on a quinodimethane‐type molecule, 2,7‐dicyanomethylene‐9‐(2‐ethylhexyl)carbazole (1), one of the shortest π‐conjugated biradicaloids reported to be stable in solution under ambient conditions. This carbazole‐based quinoidal precursor is able to form a macrocyclic σ‐bonded tetramer (2). The resolved single‐crystal X‐ray structure of tetramer 2 shows that four molecules of 1 are linked together through four long (CN)2C−C(CN)2 bonds (1.631 Å) resulting from coupling of the unpaired electrons in biradicaloid 1. Dynamic interconversion between monomer 1 and cyclophane tetramer 2 is achieved by reversible cleavage and recovery of the four (CN)2C−C(CN)2 bonds upon soft external stimuli (light absorption, temperature and pressure), which is accompanied by significant color changes. These novel photo‐, thermo‐, and mechanochromic properties expand the versatility of π‐conjugated biradicaloid compounds as novel functional materials that, in combination with spin chemistry and dynamic covalent chemistry, can be relevant in molecular machines, sensors, and switches.
AB - This work reports on a quinodimethane‐type molecule, 2,7‐dicyanomethylene‐9‐(2‐ethylhexyl)carbazole (1), one of the shortest π‐conjugated biradicaloids reported to be stable in solution under ambient conditions. This carbazole‐based quinoidal precursor is able to form a macrocyclic σ‐bonded tetramer (2). The resolved single‐crystal X‐ray structure of tetramer 2 shows that four molecules of 1 are linked together through four long (CN)2C−C(CN)2 bonds (1.631 Å) resulting from coupling of the unpaired electrons in biradicaloid 1. Dynamic interconversion between monomer 1 and cyclophane tetramer 2 is achieved by reversible cleavage and recovery of the four (CN)2C−C(CN)2 bonds upon soft external stimuli (light absorption, temperature and pressure), which is accompanied by significant color changes. These novel photo‐, thermo‐, and mechanochromic properties expand the versatility of π‐conjugated biradicaloid compounds as novel functional materials that, in combination with spin chemistry and dynamic covalent chemistry, can be relevant in molecular machines, sensors, and switches.
U2 - 10.1002/chem.201702659
DO - 10.1002/chem.201702659
M3 - Article
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
SN - 0947-6539
ER -