Glycyl-L-phenylalanine peptide based Schiff base dual ion selective fluorescent chemosensor: Synthesis, detection of Zn2+ and Al3+, real water sample analysis and DFT study

Jagritima Chetia; Hunshisha Pyngrope; Bandashisha Kharpan; Somnath Chanda; Akhilesh Jaiswar; Amit Kumar Pradhan; Pradip C Paul

doi:10.1016/j.saa.2025.126489

Glycyl-L-phenylalanine peptide based Schiff base dual ion selective fluorescent chemosensor: Synthesis, detection of Zn²⁺ and Al³⁺, real water sample analysis and DFT study

Spectrochim Acta A Mol Biomol Spectrosc. 2025 Dec 5:342:126489. doi: 10.1016/j.saa.2025.126489. Epub 2025 May 28.

Authors

Jagritima Chetia¹, Hunshisha Pyngrope¹, Bandashisha Kharpan¹, Somnath Chanda¹, Akhilesh Jaiswar², Amit Kumar Pradhan³, Pradip C Paul⁴

Affiliations

¹ Department of Chemistry, Assam University, Silchar 788011 Assam, India.
² Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, West Bengal 741246, India.
³ Department of Chemistry, Indian Institute of Technology Delhi, New Delhi 110016, India.
⁴ Department of Chemistry, Assam University, Silchar 788011 Assam, India. Electronic address: pradipcpaul123@gmail.com.

PMID: 40450799
DOI: 10.1016/j.saa.2025.126489

Abstract

A glycyl-L-phenylalanine peptide-based Schiff base (HL) fluorescence probe was designed, synthesized, and characterized using various analytical techniques. The chemosensing ability of the Schiff base was explored against different metal ions. The chemosensor probe exhibited high selectivity and sensitivity towards Zn²⁺ and Al³⁺ ions, with detection limits of 1.63 × 10^-9 M and 1.25 × 10^-9 M, respectively. Job's plot analyses and the Benesi-Hildebrand relation clearly revealed a 1:1 stoichiometry between the fluorescent probe and the metal ions, with apparent binding constants of 1.02 × 105 M^-1 for Zn²⁺ and 2.39 × 105 M^-1 for Al³⁺. The emission intensity of HL remained reversible over four cycles of sequential alternate additions of Al³⁺ or Zn²⁺ ions and EDTA, demonstrating an efficient "off-on-off" fluorescence response. The compound HL represents a tunable system incorporating one OR and one INHIBIT logic gate with two distinct sets of inputs: (i) Zn²⁺ (IN1) and Al³⁺ (IN2), and (ii) Zn²⁺/Al³⁺ (IN1) and EDTA (IN2), with fluorescence emission as the output. Additionally, an IMPLICATION logic gate was achieved using Zn²⁺ (IN1), Al³⁺ (IN2), and EDTA (IN3) as inputs. Moreover, the probe demonstrated excellent potential for the quantitative detection of Zn²⁺ and Al³⁺ in real water samples across a wide pH range. The optimized molecular geometries and HOMO-LUMO energy gaps of the compounds (HL, HL-Zn²⁺, and HL-Al³⁺) were determined using Density Functional Theory (DFT) calculations.

Keywords: DFT; Dual chemosensor; Logic gate; Peptide-based Schiff base; Real sample analysis.