Synthesis and Functions of Oligomeric and Multidentate Dipyrrin Derivatives and their Complexes

Abstract

The dipyrrin–metal complexes and especially the boron complex 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) have recently attracted considerable attention because of their interesting properties and possible applications. We have developed two unique and useful ways to extend versatility and usefulness of the dipyrrin complexes. The first one is the linear and macrocyclic oligomerization of the BODIPY units. These arrangements of the B–F moieties of the oligomerized BODIPY units provide sophisticated functions, such as unique recognition ability toward cationic guest, associated with changes in the photophysical properties by utilizing unprecedented interactions between the B–F and a cationic species. The second one is introduction of additional ligating moieties into the dipyrrin skeleton. The multidentate N2Ox dipyrrin ligands thus obtained form a variety of complexes with 13 and 14 group elements, which are difficult to synthesize using the original N2 dipyrrin derivatives. Interestingly, these unique complexes exhibit novel structures, properties, and functions such as guest recognition, stimuli-responsive structural conversion, switching of the optical properties, excellent stability of the neutral radicals, etc. We believe that these multifunctional dipyrrin complexes will advance the basic chemistry of the dipyrrin complexes and develop their applications in the materials and medicinal chemistry fields.1 Introduction2 Linear Oligomers of Boron–Dipyrrin Complexes3 Cyclic Oligomers of Boron–Dipyrrin Complexes4 A Cyclic Oligomer of Zinc–Dipyrrin Complexes5 Group 13 Element Complexes of N2Ox Dipyrrins6 Chiral N2 and N2Ox Dipyrrin Complexes7 Group 14 Element Complexes of N2O2 Dipyrrins8 Other N2O2 Dipyrrin Complexes with Unique Properties and Functions9 Conclusion

The TDDFT Excitation Energies of the BODIPYs; The DFT and TDDFT Challenge Continues

“…The BODIPY pigment and its derivatives are key entities for phototheranostics [1], including photodynamic therapy [2], functional optoelectronic materials [3], such as solar cells [4][5][6] and light emitting diodes [7], and stimuli-responsive materials [8][9][10][11]. In order to understand or predict the optical properties [12,13] of such important chromophore, and notably the lowest energy electronic transition, a very large number of investigations involving computational argumentations were reported but most of the time the correspondence between the calculated position and experimentally observed one turned out to be chronically poor, where differences ranging from 60 to 100 nm were commonly depicted [14][15][16][17][18][19][20][21][22][23][24][25][26][27].…”

Synthesis and optical properties of antimony(v) complexes of a trianionic N2O2-type tetradentate dipyrrin ligand

“…The longest maximum absorption wavelength (643 nm) of LSbCl 2 shifted to a longer wavelength compared to those of the related N 2 O 2 –dippyrin complexes of group 13 and 14 elements. 9,10 LSb(OH) 2 and LSbCl(OH) exhibited blue-shifted absorption compared with that of LSbCl 2 . Time dependent-density functional theory (TD-DFT) calculations revealed that the longest absorptions of these complexes could be attributed to their HOMO–LUMO transitions, and the frontier orbitals were distributed over the ligand π-systems.…”

“…8 We utilised the N 2 O 2 -type dipyrrin ligands to synthesise complexes with group 13 (B, 9 Al, Ga, and In) and group 14 (Si, Ge, and Sn) elements (Fig. 1); 10 however, a zwitterionic dipyrrin VII was obtained instead of the P( iii )–dipyrrin complex. 11 Further, it is hypothesized that the complexation of N 2 O 2 -type dipyrrin ligands with heavier group 15 elements (As, Sb, and Bi) could yield air- and moisture-stable complexes.…”