RESUMO
The simple reaction of phenylthiol with 8-MeS-BODIPY (1) in dichloromethane was readily accomplished to form 8-PhS-BODIPY (2). If the reaction is performed in THF 3,8-bis(phenylthio)-BODIPY (3) and 3,5,8-tris(phenylthio)-BODIPY (4) are sequentially formed in an unprecedented reaction. This provides a simple new methodology for the introduction of the phenylthio-moiety in the 3- and 5-positions. Alkyl thiols do not form multi-thiolated products under identical conditions, as exemplified using EtSH, where only 8-EtS-BODIPY (5) is formed.
Assuntos
Compostos de Boro/química , Corantes Fluorescentes/química , Compostos de Sulfidrila/química , Cor , Modelos Moleculares , Conformação Molecular , Solventes/químicaRESUMO
New 8-NR2-BODIPYs, R2 = H(i)Pr (3a), H(i)Bu (3b), and Et2 (4), are reported. Restricted rotation about the C8-N bond in such molecules has been observed for the first time (3a and 3b) and evaluated using VT NMR. The fluorophores 3a and 3b are blue emitters, and the efficiency of the emission is closely related to the polarity of the solvent, e.g., hexane > toluene > DCM > THF > MeOH > H2O, an effect also noted by emission variation in alcohol solvents H(CH2)nOH, n = 1-6. In mixed-solvent systems, addition of 10-15% of the more polar solvent results in transformation of the emission properties to those of the bulk polar solvent. Compound 4 has zero emission in all solvents. The crystal structures of 3a, 3b, and 4 are reported, along with that of the parent 8-NH2-BODIPY (2). Compounds 2, 3a, and 3b exhibit trigonal planar N atoms which are coplanar with the BODIPY core; 4 exhibits a very significant distortion that breaks the planarity of the extended BODIPY π system due to the steric impact of the two ethyl groups, an observation that explains the lack of emission for 4.