Conformational study of an axially chiral Salen ligand in solution using two-photon circular dichroism and the fragment-recombination approach.
Herein we report on the conformational study of a chiral Salen ligand, AFX-155, in THF solution using two-photon absorption (TPA) and, even more importantly, two-photon circular dichroism (TPCD). The fragment-recombination approach (FRA), employed to perform computations on half-AXF-155 (AXF-169') and the center (C-AXF-155), allowed us to overcome the current computational limitations found in calculations of the TPCD spectra of large molecules. The comparative experimental-theoretical analysis of AXF-155 showed that its TPA is mainly determined by AXF-169' and validated, through TPCD, the presence of the two dominant Trans_R-Intra(NHB)//Trans_R-Extra(HB) and Trans_R-Intra(NHB)//Trans_R-Extra(NHB) structure in THF with a ΔΔ propeller chirality on the diphenylamine moieties at the end of each AXF-169'. The application of FRA for the analysis of the TPCD spectra of large chiral molecules has been proven to be effective.
Department of Chemistry, University of Central Florida, P.O. Box 162366, Orlando, Florida 32816-2366, USA.
Carlos
C
Díaz
Lorenzo
L
Echevarria
Florencio E
FE
Hernández
D000814:Aniline Compounds / Q000737:chemistry*; D002942:Circular Dichroism; D003198:Computer Simulation; D004159:Diphenylamine / Q000737:chemistry; D005029:Ethylenediamines / Q000737:chemistry*; D008024:Ligands; D008968:Molecular Conformation; D009281:Naphthalenes / Q000737:chemistry*; D012996:Solutions; D013237:Stereoisomerism
C587807:((E)-4-((7-(diphenylamino)-9,9-dihexyl-9H-fluoren-2-yl)ethynyl)-2-((naphthalen-2-ylimino-1-methyl)methyl)phenol); D000814:Aniline Compounds; D005029:Ethylenediamines; D008024:Ligands; D009281:Naphthalenes; D012996:Solutions; C011452:disalicylaldehyde ethylenediamine; D004159:Diphenylamine