Calixsmaragdyrin: A Versatile Ligand for Coordination Complexes.
The Ru(II) and BF2complexes of calixsmaragdyrin were prepared under simple reaction conditions and characterized by HR-MS, 1D and 2D NMR spectroscopy, optical spectroscopy, and electrochemistry, and the structure of the Ru(II) complex of calixsmaragdyrin was elucidated by X-ray crystallography. The crystal structure of the Ru(II) complex revealed that the Ru(II) ion is hexacoordinate with the three pyrrole nitrogen ligands from the tripyrrin unit of the calixsmaragdyrin macrocycle, and the remaining coordination sites of Ru(II) ion were occupied by two carbonyl groups and one hydroxyl (-OH) group. The calixsmaragdyrin macrocycle in the Ru(II) complex was distorted with a dome-like structure. In the BF2complex of calixsmaragdyrin, the BF2unit was bound to two pyrrolic nitrogens of the dipyrrin moiety of calixsmaragdyrin as deduced by detailed 1- and 2-dimensional NMR spectroscopy studies. The Ru(II) complex displayed a strong Soret-like absorption band at 449 nm with the absence of Q-bands, whereas the BF2complex showed a Soret-like band at 475 nm with two well-defined Q-bands at 787 and 883 nm, respectively. Quantum mechanical DFT calculations yielded relaxed equilibrium structures that were similar to the X-ray crystal structures, and the related charge density distributions indicated that the d orbital of the Ru(II) ion was contributing to the HOMO and LUMO states. In addition, TD-DFT calculations successfully reproduced the large bathochromic shifts, oscillator strengths, and electronic transitions that were observed in the experimental absorption spectra of all three complexes. Both the Ru(II) and the BF2complexes of calixsmaragdyrin were stable under redox conditions.
Department of Chemistry, Indian Institute of Technology Bombay , Powai, Mumbai 400076, India.
Tamal
T
Chatterjee
Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute , Troy, New York 12180, United States.
Brian
B
Molnar
Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute , Troy, New York 12180, United States.
G G
GG
Theophall
Instrumentation Center, Department of Chemistry, National Taiwan Normal University , 88 Section 4 Ting-Chow Road, Taipei 11677, Taiwan.
Way-Zen
WZ
Lee
Department of Chemistry and Chemical Biology and The Baruch '60 Center for Biochemical Solar Energy Research, Rensselaer Polytechnic Institute , Troy, New York 12180, United States.
K V
KV
Lakshmi
Department of Chemistry, Indian Institute of Technology Bombay , Powai, Mumbai 400076, India.
Mangalampalli
http://orcid.org/0000-0003-0193-6081
M
Ravikanth