Chromogenic Chemosensors Based on Phenolic Imines for the Detection of Alkylamines and Lidocaine in Water and in the Vapor Phase

Abstract

Three imines comprised of 5-nitrothiophen-2-yl as electron-accepting and phenols as electrondonating groups were synthesized and used as chromogenic chemosensors to detect alkylamines. The compounds are colorless in water, but their deprotonation by the alkylamines generates the corresponding colored phenolates, which can be used to detect those analytes. The addition of cetyltrimethylammonium bromide (CTAB) causes bathochromic shift of the perichromic band of the phenolates, indicating that the compounds are transferred into the micelles. In addition, CTAB lowers the pKa of phenols and increases the stability of the phenolates, improving their performance as chemosensors. Applications were prospected with the chromogenic chemosensors adsorbed on strip papers to detect alkylamines in water and in the vapor phase. The compounds were also used in solution for the quantification of lidocaine in water. Thus, the versatility of the compounds studied allows to think about applications in industrial, environmental, and pharmaceutical areas.

Planar in Brooker's mode and twisted in Reichardt's mode: defying the steric forces in biphenyl types of zwitterionic systems through metameric resonance stabilizations

“…1, where the steric constraints are prevalent in both cases (leaving no room for steric relaxations as the influential factor for conformational preferences). [18][19][20] Two zwitterionic molecules have pyridinium (+vely charged) as the acceptor and phenolate (Àvely charged) as the donor, but they differ with respect to the connectivity around the pyridinium N-atoms. [18][19][20] Here, they are represented as the Reichardt's type metamer 21 and Brooker's type metamer.…”

“…[18][19][20] Two zwitterionic molecules have pyridinium (+vely charged) as the acceptor and phenolate (Àvely charged) as the donor, but they differ with respect to the connectivity around the pyridinium N-atoms. [18][19][20] Here, they are represented as the Reichardt's type metamer 21 and Brooker's type metamer. 22 Quantum chemical investigations on the structures of these two metameric zwitterion molecules were carried out using various well-known methodologies, and the possible reasons for the exhibition of such differential behaviours are outlined in this contribution.…”

Better performances of benzene‐based over thiophene‐based aromatic anionic donors: Computational studies on metameric conformational selectivity and hyperpolarizability of organic inner salts

“…Recently, concept of metamerism was extended to biaryl types of zwitterionic systems to show how it affects the conformation selectivity in a metameric pair 1 . Biaryls are interesting, because they can adopt twisted or planar conformations, based on the nature of interactions (either destabilizing steric repulsions or resonance‐assisted conjugation and/or hydrogen bonding stabilizations) existing at their aryl–aryl junction sites 2–14 . In the recent work of Sitha, it was shown that even with steric interactions being prevalent at the aryl–aryl junctions (steric forces give the molecule a twisted conformation), one can still achieve a stable planar conformation by inducing metamerism in zwitterions 1 .…”

“…1 Biaryls are interesting, because they can adopt twisted or planar conformations, based on the nature of interactions (either destabilizing steric repulsions or resonance-assisted conjugation and/or hydrogen bonding stabilizations) existing at their aryl-aryl junction sites. [2][3][4][5][6][7][8][9][10][11][12][13][14] In the recent work of Sitha, it was shown that even with steric interactions being prevalent at the aryl-aryl junctions (steric forces give the molecule a twisted conformation), one can still achieve a stable planar conformation by inducing metamerism in zwitterions. 1 As demonstrated, a Reichardt's type 15 zwitterion adopted a twisted conformation (surrendering to mighty steric forces), and at the same time, a Brooker's type 16 zwitterion adopted a full planar conformation (metameric resonance stabilization overpowered the repulsive steric interactions).…”

Metameric influences on conformational selectivity for zwitterionic pyridinium cyclopentadienide and its aza analogues. Quantum mechanical studies on linear and nonlinear optoelectronic properties

“…In a recent work, the concept of metamerism (special type of isomerism) was introduced to control the highly influential mighty steric force [18]. This investigation clearly shows that, with the steric constraints being prevalent (with their full potentials) at the aryl‐aryl junctions, which spares no rooms for steric relaxation as the influential factor for conformational preferences [19–21], still one can induce a conformational preference through the force of resonance stabilizations. In this interesting report, it was shown how zwitterion representing the Reichardt's mode of bonding [22] preferred the twisted type of conformation, and molecule representing Brooker's mode bonding [23] preferred the fully planar conformation, due to substantial contributions from resonance stabilizations.…”