Open AccessExperimental and computational studies on a protonated 2-pyridinyl moiety and its switchable effect for the design of thermolytic devices
Author(s) -
Jolanta Brzezińska,
Jacek Kujawski,
Agnieszka Witkowska,
Kornelia Czaja,
Marek K. Bernard,
Marcin K. Chmielewski
Publication year - 2018
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0203604
Subject(s) - protonation , moiety , chemistry , intramolecular force , aromaticity , substituent , computational chemistry , thermolabile , stereochemistry , molecule , organic chemistry , ion , enzyme
1D and 2D NMR investigations as well as computational studies, including static quantum-mechanics calculations, density function theory formalism, and classical molecular dynamics, were applied to determine the protonation sites in the thermolabile protecting group (TPG) containing a 2-pyridynyl moiety within its structure. This protecting group has three possible sites for protonation: an azomethine (pyridinic) atom ( N1 ), 2-aminoethanol residue ( N2 ), and 4-amino substituent ( N4 ). Our investigations showed that the protonation mainly occurs on the N1 atom. Such protonation seems to be a major inhibitory factor in the thermal removal of 2-pyridynyl TPG by the “chemical switch” approach and decreases the aromaticity of the pyridine ring. We also discussed possible participation of N 2 nitrogen in irreversible intramolecular cyclization under acidic conditions.