title: Excited state behavior of pyrrole 2-carboxyldehyde: theoretical and experimental study.
abstract: Photophysical and photochemical dynamics of excited state proton transfer reaction have been reported for Pyrrole 2-carboxyldehyde (PCL). Experimental and theoretical observations yield all possible signatures of intramolecular and intermolecular proton transfer in an excited state. Dual emission (~325 nm, ~375 nm) on photo excitation indicates the existence of more than one species in an excited state. Computed reaction pathway and two-dimensional potential energy profile in the ground state reveals a single minimum corresponding to normal form (E). Dual minima in excited state energy profile shows the existence of two species, one normal and other zwitterionic (Z*) species. A large Stokes shifted emission at ~375 nm in hydrocarbon medium reveals the existence of zwitterionic species due to Excited state intramolecular proton transfer (ESI(ra)PT). Excited State Intermolecular proton transfer (ESI(er)PT) is observed in a hydroxylic environment around 430-490 nm. pH variation in hydroxylic medium suggests the formation of anion (A((-))) from Z*.
authors.affiliation: Department of Physics and Materials Science & Engineering, Jaypee Institute of Information Technology, Noida, Uttar Pradesh 201 307, India.
authors.forename: Nidhi
authors.initials: N
authors.lastname: Singla
authors.forename: Rakesh
authors.initials: R
authors.lastname: Kumar
authors.forename: Anirban
authors.initials: A
authors.lastname: Pathak
authors.forename: Papia
authors.initials: P
authors.lastname: Chowdhury
mesh_terms: D000838:Anions / Q000737:chemistry; D008958:Models, Molecular; D011522:Protons; D011758:Pyrroles / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics
chemical_list: D000838:Anions; D011522:Protons; D011758:Pyrroles