Boron calixphyrin complexes: exploring the coordination chemistry of a BODIPY/porphyrin hybridElectronic supplementary information (ESI) available: NMR spectra for all compounds, details of X-ray crystallography data collection and structure solution, data for kinetic studies, DFT Cartesian coordinates and optimised structures. CCDC 1587634-1587637. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7dt04575a

• Main Authors: Tay, Aaron Chin Yit, Frogley, Benjamin J, Ware, David C, Brothers, Penelope J
• Format: Journal Article
• Language: English
• Published: 06.03.2018
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c7dt04575a

Boron complexes of calix[4]phyrins ( 1 . 1 . 1 . 1 ) were prepared by reacting the free-base ligands with BF 3 ·Et 2 O. The reaction conditions can be efficiently tailored to produce mono- or di-boron calixphyrins. Mono-BF 2 calixphyrins with boron coordinating to either the dipyrrin, BF 2 [H(Calix)], or dipyrromethane, BF 2 [H(Calix)] and BF 2 [H 2 (Calix)] + , bonding sites were isolated. The dipyrromethane isomer, BF 2 [H(Calix)], isomerises into BF 2 [H(Calix)] which kinetic studies and DFT calculations indicate is an intramolecular process. Two isomers of B 2 OF 2 (Calix) were isolated, one isomer bonding via the dipyrrin sites with the FBOBF moiety in cisoid geometry, and the second isomer bonding via the dipyrromethane sites with the FBOBF moiety in transoid geometry. Although the cisoid /dipyrrin isomer was calculated to be most energetically favourable for B 2 OF 2 (Calix), the isolation of the transoid /dipyrromethane isomer is postulated to occur via the presumed intermediate (BF 2 ) 2 (Calix), for which DFT indicated a preference for transoid /dipyrromethane geometry. Calix[4]phyrin ( 1 , 1 , 1 , 1 ) proves to be a versatile ligand for boron with both mono- and di-boron complexes exhibiting unusual regio- and stereoisomerism.