Spin-Crossover Anticooperativity Induced by Weak Intermolecular Interactions.
As a rule, rational design of cooperative spin-crossover (SCO) molecular switches is largely based on consideration of sizes and structures of individual building blocks, whereas a meticulous analysis of crystal packing, including the weakest intermolecular interactions, is often assumed to play a secondary role or is even fully neglected. By investigating cobalt(II) clathrochelates, which do not change the molecular volume upon SCO, we showed that even weak (1.2 kcal/mol) π···Cl intermolecular interactions can cause a pronounced anticooperativity of SCO, being more gradual in the solid state than in solution. Our results clearly demonstrate that the "chemical pressure" concept is not as general as it is thought to be, and the successful design of molecular switches requires in-depth analysis of intermolecular interactions, however weak they seem.
†Nesmeyanov Institute of Organoelement Compounds RAS Vavilova, 28, Moscow 119991, Russia.
Valentin V
VV
Novikov
†Nesmeyanov Institute of Organoelement Compounds RAS Vavilova, 28, Moscow 119991, Russia.
Ivan V
IV
Ananyev
†Nesmeyanov Institute of Organoelement Compounds RAS Vavilova, 28, Moscow 119991, Russia.
Alexander A
AA
Pavlov
‡International Tomography Center, SB RAS, Institutskaya 3A, Novosibirsk 630090, Russia.
Matvey V
MV
Fedin
†Nesmeyanov Institute of Organoelement Compounds RAS Vavilova, 28, Moscow 119991, Russia.
Konstantin A
KA
Lyssenko
†Nesmeyanov Institute of Organoelement Compounds RAS Vavilova, 28, Moscow 119991, Russia.
Yan Z
YZ
Voloshin
clathrochelates; cobalt(II); cooperativity; macrocyclic compounds; molecular switches; spin crossover