Position Of Porphyrin Research Articles

Water Soluble Porphyrin for the Fluorescent Determination of Cadmium Ions.

Porphyrins are highly conjugated molecules that perform wide variety of functions in biological systems. They absorb strongly in the visible region and they are excellent fluorophores that emit in the visible region. If the meso or β positions of porphyrins are properly substituted, emission in the NIR region is facilitated. The fluorescence property of porphyrins can be used in sensing applications. Here, we report the synthesis of a water soluble porphyrin that emits in the NIR region and this molecule is used in the fluorescent determination of cadmium ion, which is an environmental pollutant and affects the health of living organisms adversely. 5,10,15,20-tetrakis(4-hydroxy-3,5-dimethoxyphenyl)porphyrin (THMPP), which is water soluble was synthesised from 5,10,15,20-tetrakis(3,4,5-trimethoxyphenyl)porphyrin (TMPP) by partial demethylation, which in turn was synthesized by mixture acid method. The donor-acceptor interaction of THMPP-Cd2+ system displays a dynamic fluorescence quenching through the electron transfer (ET) mechanism. Developed method showed a linear response toward Cd2+ in the concentration range of 0.25μM to 2μM. The limit of detection was found to be 0.1499μM. THMPP exhibited excellent selectivity towards Cd (II) in presence of other metal ions like Hg2+, Mn2+, Mg2+, Co2+ in 1:100, Zn2+, Cu2+, Ni2+ in 1:10 and Na+, K+ in 1:1M ratio.

Strong, near-infrared absorbing porphyrins: a DFT study

A systematic density functional theory study of electronic properties and optical spectra of four potential fused porphyrins with extended π-conjugation has been reported employing the M06 functional along with 6-31G(d)+LanL2DZ basis set. Symmetrical tetra fusion of the benzene rings at the β-meso-β position of porphyrins, resulted in four quadruply fused porphyrins. Such studies revealed the fact that the ring fusion with extended π-electrons causes remarkable red-shifts with narrowed band gaps. Thus, such systems can be used to extend the absorption deeper in to near-infrared (NIR) to even better utilize the photon rich region of solar spectrum. These fused porphyrins have emerged as promising NIR absorbing materials, having utility in molecular solar-conversion systems.

Influence of the number of phenylethynyl units present in porphyrin sensitizer on its light harvesting and cell performance

Four phenylethynyl-porphyrins 4a, 4b, 5a, and 5b with either one (4a and 4b) or two (5a and 5b) phenylethynyl groups attached at C10 or/and C20 position of the porphyrin ring (defined as the axial direction), and with phenyl (4a and 5a) or 2,6-dialkoxylphenyl group (4b and 5b) at C5 position of porphyrin in a push–pull framework (defined as the push–pull direction) were designed and synthesized. The synthesized porphyrins were applied in dye-sensitized solar cells (DSSCs). Unexpectedly, although the light harvesting capability of the dye is enhanced with the increase of the number of phenylethynyl group as indicated in the UV–Vis spectra, the light to electricity conversion efficiency (η) of the corresponding solar cell drops. The influence of the number of the phenylethynyl group present along the axial direction of the porphyrin on the photovoltaic performance of DSSCs is well explained by the condensed Fukui function obtained via DFT calculations.

ChemInform Abstract: One-Pot Synthesis of Functionalized Asymmetric 5,10,15,20-Substituted Porphyrins from 5,15-Diaryl- or -Dialkyl-porphyrins.

Abstract Reaction of easily available (5,15-dialkyl/arylporphyrinato)nickel(II) with RLi under anhydrous conditions affords 5,10,15-trisubstituted porphyrin anions that can be used as in situ nucleophiles for reaction with alkyl iodide reagents. After oxidation with atmospheric oxygen, 5,10,15,20-tetrasubstituted porphyrins are obtained in good yields. This method permits introduction of all base-stable functional groups into the meso position of porphyrins.