Sensitive Hg2+ Sensing via Quenching the Fluorescence of the Complex between Polythymine and 5,10,15,20-tetrakis(N-methyl-4-pyridyl) Porphyrin (TMPyP)

Abstract

The interaction between polythymine (dTn) and 5,10,15,20-tetrakis(N-methyl-4-pyridyl) porphyrin (TMPyP) was systematically studied using various techniques. dTn remarkably enhanced the fluorescence intensity of TMPyP as compared to other oligonucleotides. The enhanced fluorescence intensity and the shift of the emission peaks were ascribed to the formation of a π-π complex between TMPyP and dTn. And the quenching of the dTn-enhanced fluorescence by Hg2+ through a synergistic effect occurs due to the heavy atom effect. The binding of Hg2+ to TMPyP plays an important role in the Hg-TMPyP-dT30 ternary complex formation. A TMPyP-dT30-based Hg2+ sensor was developed with a dynamic range of Hg2+ from 5 nM to 100 nM. The detection limit of 1.3 nM was low enough for Hg2+ determination. The sensor also exhibited good selectivity against other metal ions. Experiments for tap water and river water demonstrated that the detection method was applicable for Hg2+ determination in real samples. The Hg2+ sensor based on oligonucleotide dT30-enhanced TMPyP fluorescence was fast and low-cost, presenting a promising platform for practical Hg2+ determination.

Adsorchromism: Molecular Nanoarchitectonics at 2D Nanosheets—Old Chemistry for Advanced Chromism

“…Supplementarily, the redshift of absorption due to adsorption is also synchronized with the redshift of fluorescence spectra (𝜆 em in water, on saponite, and intercalated is 660, 688, and 715 nm, respectively.). [40][41][42] A similar spectral shift was reported for TMPyP 4+ used as a drug molecule intercalated with DNA in 1983 by Pasternack et al [43,44] Given that drug molecules are typically small, planar, and aromatic, they can slip between the base pairs of doublestranded nucleic acids without major distortion. However, the intercalation of TMPyP 4+ with DNA was accompanied by an unexpected large absorption band shift, given that the mesosubstituents are nearly co-planar to the plane of the porphyrin ring.…”

“…Supplementarily, the redshift of absorption due to adsorption is also synchronized with the redshift of fluorescence spectra ( λ em in water, on saponite, and intercalated is 660, 688, and 715 nm, respectively.). [ 40 , 41 , 42 ]…”

Structure and photophysical and electrochemical properties of a copper porphyrin complex with a three-dimensional framework

“…As far as is known, porphyrins are famous for their vital roles in the red blood cells of animals and the green leaves of plants; as a result, porphyrins have become one of the most widely investigated chemical systems and have drawn much attention as wonderful functional materials. Due to their comparability to the natural photosynthetic chlorophyll pigment, easy preparation, intensive optical absorptions and emissions, long lifetimes of the singlet and triplet states, and favourable redox potential (Kadish et al, 2000;Chambron et al, 2000;Gust & Moore, 2000), porphyrins offer a very versatile synthetic base for many kinds of materials which have different applications in many disciplines of physics and chemistry, such as solar cells and opto-electronics (Khan & Sayyad, 2012;Seol et al, 2012;Arkan et al, 2015;Xia et al, 2015;Ørnsø et al, 2015), catalysis (Chen et al, 2019;Zhang et al, 2018;Mokary Yazdely et al, 2019), sensors (Ma et al, 2019;Wu et al, 2018;Zhao et al, 2019) and molecular sieves (Anjali et al, 2018;Hou et al, 2014).…”