Inclusive DFT insight into sensing mechanism of cyclotetrapyrole towards lung irritants

Abstract

The development of smart sensing devices for toxic analytes detection especially lung irritants is much essential. The cyclic conducting polymers having in nite 𝜋-conjugation are proved to be highly sensitive for toxic analytes. Herein, by using the DFT approach, we investigated the sensing mechanism of cyclotetrapyrole (CTPy) for accurate detection of phosgene, diphosgene, chloropicrin and chlorine at the B3LYP-D3/6-31+ G (d, p) level. The calculated interaction energies show the physisorption of lungs irritants over the CTPy surface. Natural bond orbital (NBO) and charge decomposition (CDA) analyses predict charge transfer interactions in the complexes. The reduced density gradient (RDG) approach reveals that charge transfer electrostatic hydrogen bonding interactions dominate in the complexes. The sensitivity of CTPy towards lung irritants is further illustrated by the reduction in HOMO-LUMO energy gaps, red shifting of λ max in UV-Visible specta. Density of state (DOS) analysis a rm that enhanced conductivity upon complexation is due to the origination of new energy states in occupied and virtual orbitals nearer to the Fermi level. Moreover, PDOS spectra show that CTPy primarily contributes to the energy of HOMO. The outcome of the current study depicts appreciable sensitivity of CTPy towards lung irritants. We believe that the upshot of the current ndings and their forecasts will provide useful guidelines for an experimentalist to design highly sensitive sensors for toxic analytes using CTPy. Highlights 1. The highest Q NBO transfer towards the analyte (−0.121) is seen in the chlorine@CTPy complex.2. The highest reduction in E g (61 %) betweenoccupied and virtual orbitals is noticed in chlorine@CTPy.3. The orbital overlap results in a 41 % red shifting of in chlorine@CTPy. 4. Cyclotetrapyrole is highly sensitive for chlorine.

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