Porphyrin Arrays Responsive to Additives. Fluorescence Tuning

Abstract

The application of low-flux sunlight begins with the synthesis of effective antenna systems. This requires the development of dye integrates with optimized dye orientation for effective energy transfer. We here report a series of peptide-linked porphyrin arrays, denoted by Boc-(Por(Zn,S))(n)-OBu(t) (n = 2, 4, and 8), that change their dye orientation to increase fluorescence responsively to additive reagents. The B-band absorption (AB) regions of the arrays show blue shifts (dimer, 407.6 nm; tetramer, 408.2 nm; octamer, 407.8 nm) in organic solvents as compared to that of Boc-Por(Zn,S)-OBu(t) (monomer, 422.6 nm) and the fluorescence yield Phi' of the arrays decreases with increasing n, obeying the relationship Phi' = 0.03/n(1.5); however, the arrays are tuned up in fluorescence emission by the addition of 1,2-diaminoethane (en). The addition of a sufficient amount of en increases the fluorescence of the porphyrins in monomer, dimer, tetramer, and octamer by approximately 5, approximately 12, approximately 12, and >730 times, respectively, when compared with that observed in the absence of en. This also causes asymptotic red shifts in absorption (AB) bands (B-band lambda(max): 410 to 429-430 nm), as well as changes in circular dichroism (CD) spectra, and makes porphyrins approach new mutual asymmetric orientations. Our results show the potentiality of the tunable dye polymers that are a posteriori optimized in dye orientation and fluorescence emission by additive reagents for the development of effective light-harvesting materials.

Novel nanographene/porphyrin hybrids – preparation, characterization, and application in solar energy conversion schemes

“…37,39 The Vilsmeier formylation of tetraalkylporphyrins has been reported previously albeit in very low yields. 40,41 We also found that using the DMF-POCl 3 formylation complex at 80-90 C produces mostly decomposition products. Shortening the reaction time to 50 min gave 2 in low yield (<20%) with recovery of some unreacted 1, whilst lowering the reaction temperature below 70 C did not give any appreciable product.…”

“…37 Usage of such harsh conditions decreases the yield of the free-base tetraalkylporphyrin. 41 As a result, we have utilized here the milder procedure described by Ponomarev and Maravin. 42 A cooled solution of porphyrin 2 dissolved in a small amount of POCl 3 is treated with water (10% by volume).…”

Porphyrin-based sensor nanoarchitectonics in diverse physical detection modes

“…6). 52 The Soret band of the arrays exhibited blue shifts in organic solvents compared to that of the monomer, and the fluorescence yield of the arrays decreased with increasing unit numbers. By balancing the van der Waals interactions, p-p interactions, ligand coordination, and formation of peptide secondary structure, appended porphyrins in the array maintain their mutual orientation.…”

High Conductive Two-Dimensional Covalent Organic Framework for Lithium Storage with Large Capacity

“…46,47 The Q-bands were also observed to be redshifted to 558 and 596 nm, respectively, suggesting that the porphyrin molecule was in a face-to-face-packing in TThPP film. 48 TThP showed two obvious fluorescence peaks at 661 and 720 nm, respectively, whereas the TThPP film red-shifted to 668 and 725 nm. The intensity ratio of the peak at 668 to 725 nm of the TThPP film increased as compared to that of TThP, suggesting the increase of the planarity of porphyrins in the polymer.…”