Azadipyrromethene‐Based Near‐Infrared Dyes: Effect of Thienylethynyl Substitution at the Distal and Proximal Phenyl Groups

Abstract

Azadipyrromethene (ADP) ligands substituted with thienylethynyl substituents either at the distal phenyl groups H(CD1) or the proximal phenyl groups H(CD2) were synthesized and characterized. The thienyl groups have a hexyl group at the third position to improve solubility in organic solvents and prevent homocoupling of the ethynylthiophene reactants. To further tune the opto-electronic properties, the substituted ADPs were coordinated with BF 2 + and Zn II . Absorption spectroscopy shows that the thienylethynyl substitu-

Conductance Behavior of Tetraphenyl-Aza-BODIPYs

“…As such, the absorbance and emission spectra of the aza-BODPYs (11)(12)(13) were recorded in solvents with different polarities, DCM (ε r , 8.93), THF (ε r , 7.60), EtOAc (ε r , 6.02), CHCl 3 (ε r , 4.81), and toluene (ε r , 2.38), with solubility preventing measurements in cyclohexane and acetonitrile. Each of the complexes displayed a S 0 → S 1 band at 600−800 nm with S o → S 2 transition at 519−590 nm (see Figure 2); 18 this is significantly red-shifted relative to the parent aza-BODIPY and the methoxy analogue (λ abs max = 691 nm). 21 As the S 0 → S 1 transition is purely HOMO → LUMO in character, a comparison can be made with the electrochemical data, showing approximately the same trend ΔE echem |HOMO− LUMO| = 11 < 13 < 12 and absorbance ΔE abs |HOMO− LUMO| = 13 ≤ 11 < 12.…”

“…Each of the complexes displayed a S0→S1 band at 600-800 nm with So→S2 transition at 519-590 nm (see Figure 2); 18 this is significantly red-shifted relative to the parent aza-BODIPY and the methoxy analogue (λabs max = 691 nm). 21 As the S0→S1 transition is purely HOMO→LUMO in character, a comparison can be made with the electrochemical data, showing approximately the same trend ΔEechem|HOMO-LUMO| = 11<13<12 and absorbance ΔEabs|HOMO-LUMO| = 13≤11<12.…”

“…Conversion to their BF 2chelates, 11 and 12, was achieved by stirring BF 3 •OEt 2 with Et 3 N and the corresponding aza-DPY (8 and 9). Due to solubility limitations, the synthesis of 13 deviated from the established approach of Bouit et al and Bellier et al, 16,17 instead using Daddario et al's method, 18 performing a Sonogashira coupling on a bromo-substituted aza-DIPY precursor. Sonogashira coupling was performed with 1-(4bromophenyl)-3-(4-(methylthio)phenyl)-4-nitrobutan-1-one (6) and 4-ethynythioanisole to give 3-(4-(methylthio)phenyl)-1-(4-((4-(methylthio)phenyl)ethynyl)phenyl)-4-nitrobutan-1one (7); the synthesis then followed O'Shea's approach to give the corresponding aza-DIPY (10) and aza-BODIPY (13).…”

Azadipyrromethenes: from traditional dye chemistry to leading edge applications

“…This has been described for both tetraaryl azadipyrromethene 3, their BF 2 chelates 29 and zinc complexes. [71][72][73][74][75] Representative examples and conditions are shown in Scheme 28. This versatile approach has been exploited to substitute with ethynyl-(hexyloxy)-benzene, 71 ethynyl fluorescein diacetate, 72 ethynyl-N,N-dihexylaniline 71,73 and ethynyl nitrofluorene 74 groups to produce the constructs 56.…”