Cyclo-biphenalenyl biradicaloid molecular materials: conformation, tautomerization, magnetism, and thermochromism
- ORNL
- Georgetown University
Phenalenyl and its derivatives have recently attracted a great deal of interest as a result of a 2-electron multicenter (2e/mc) covalent pi-pi bonding between two pi-stacked phenalenyl units. The 2e/mc bonded pi-dimers are close in energy to the sigma-dimers of phenalenyl and therefore fickle properties may emerge from bond fluctuation, yielding smart pi-functional materials. Here we examine the valence tautomerization of two cyclo-biphenalenyl biradicaloid molecular materials with chair- and boat-conformations by spin-restricted (R) and unrestricted (U) DFT using the M06 and B3LYP functionals. We found that the chair-conformation involves a 2e/4c pi-pi bonded structure while the boat-conformation involves a 2e/12c pi-pi bonded structure on their potential energy surfaces. The global minimum for the chair-conformation is the sigma-bonded structure while it is the pi-pi bonded structure for the boat-conformation. The chair-conformation exhibits a stepwise [3,3]-sigmatropic rearrangement, and calculations predict a negligible paramagnetic susceptibility near room temperature. In comparison, the paramagnetism of the boat-conformation should be observable by SQUID and/or ESR. According to the difference of the global minima of the two conformations and the parameterized UV-Vis calculations, the color of the chair-conformation is expected to become darker while that of the boat-conformation become lighter with increasing temperature.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). National Center for Computational Sciences (NCCS)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 1004965
- Journal Information:
- Chemistry of Materials, Vol. 23, Issue 3; ISSN 0897--4756
- Country of Publication:
- United States
- Language:
- English
Similar Records
Cyclo-biphenalenyl biradicaloid molecular materials: conformation, rearrangement, magnetism, and thermochromism
The polar 2e/12c bond in phenalenyl-azaphenalenyl hetero-dimers: Stronger stacking interaction and fascinating interlayer charge transfer