Synthesis of Zinc Chlorophyll Homo/Hetero‐Dyads and their Folded Conformers with Porphyrin, Chlorin, and Bacteriochlorin π‐Systems

Abstract

Zinc complex of pyropheophorbide-b, a derivative of chlorophyll-b, was covalently dimerized through ethylene glycol diester. The synthetic homo-dyad was axially ligated with two methanol molecules from the β-face and both the diastereomerically coordinating methanol species were hydrogen bonded with the keto-carbonyl groups of the neighboring chlorin in a complex. The resulting folded conformer in a solution was confirmed by visible, (1) H NMR and IR spectra. All the synthetic zinc chlorin homo- and hetero-dyads consisting of pyropheophorbides-a, b and/or d took the above methanol-locked and π-π stacked supramolecules in 1% (v/v) methanol and benzene to give redmost (Qy) electronic absorption band(s) at longer wavelengths than those of the corresponding monomeric chlorin composites. The other zinc chlorin and bacteriochlorin homo-dyads completely formed similar folded conformers in the same solution, while zinc inverse chlorin and porphyrin homo-dyads partially took such supramolecules. The J-type aggregation to folded conformers and the redshift values of composite Qy bands were dependent on the electronic and steric factors of porphyrinoid moieties in dyads.

What can we learn from artificial special pairs?

“…10 where a zinc(II)chlorin used as model for bacteriochlorophyll is dissolved in two different solvent mixtures with different composition. 16 The presence of a bridging alkane chain secures the stoichiometry of the oligomerization to two (i.e., on itself) in diluted solution. Pyridine coordinates the zinc atom and prevents cofacial dimerization.…”

In vitro toxicity and photodynamic properties of porphyrinoids bearing imidazolium salts and N-heterocyclic carbene gold(I) complexes

“…Monocationic chlorin 14 was prepared in a twostep procedure starting from pyropheophorbide a 12 as described in literature (Scheme 6) [63][64][65][66].…”

“…MALDI-TOF + MS: calcd for C 64 H 55 Au 4 N 12 Cl 4 : 1066.38, found 1066.40.4.2.13. Pyropheophorbide a 12The synthesis and characterization data of pyropheophorbide a 12 were reported in[63][64][65][66].4.2.14. Chlorin 13Pyropheophorbide a 12 (62 mg, 0.12 mmol, 1.0 eq), 1-(3-aminopropyl)imidazole (18.6 µL, 0.16 mmol, 1.4 eq) and 4-DMAP (18.4 mg, 0.15 mmol, 1.3 eq) were dissolved in dry CH 2 Cl 2 (4.0 mL).…”

Push–pull pyropheophorbides for nonlinear optical imaging

“…[35][36][37][38] The effects of chemical modification of the -system of 1a on its optical properties have been explored in several studies. [39][40][41][42][43][44][45][46] The electronic absorption spectrum of 1a is characteristic of chlorins, and is dominated by two absorption bands, one in the high-energy region at the border of the UV (Soret band) and one in the far-red visible region (Q band). Absorption in the far-red region is useful for onephoton techniques because photo-damage is reduced at these energies compared to shorter wavelengths.…”