Relevance of pyridinylpyrazine bridged Cd(II) dimer for the trace detection of Al3+ and 4-nitroaniline in aqueous medium and electrical conductivity measurement

• Pyridyl-pyrazine bridging Cd(II) dimer with carboxylate cap from sulfosalicylic acid. • Emission of the dimer is quenched by Al 3+ and LOD is 0.1313 µM. • 4-Nitroaniline also quenches the emission of the dimer and LOD is 0.0272 µM. • The X-Ray structure of dimer shows the presence of free phenolic -OH that may be responsible the selection of analyte. • Band gap 3.20 eV insists to design Schottky device and the electrical conductivity is 2.01 × 10⁻⁶ S·m⁻¹ (dark) and 5.62 × 10⁻⁶ Sm⁻¹ (light). Polypyridine metal complexes serve as light sensitive semiconducting materials and also efficient, sensitive and selective chemosensors for the trace quantity detection of toxic ions and molecules. A Cd(II)-based coordination dimer, {[(HSSA) 2 Cd 2 (μ-tppz)(H₂O) 4 ]·H₂O.CH₃OH}, 1 , bridged by 2,3,5,6-tetrakis(2-pyridyl)pyrazine (tppz), and end capping carboxylate-O,O chelation by sulfosalicylic acid (H₃SSA) acts as strongly emissive (λ em = 402 nm) material which is quenched by Al 3+ with a detection limit (LOD), 0.1313 µM and a Stern-Volmer constant (K sv ), 4.85 × 10⁴ M⁻¹ in methanol-water (1:40, v/v). In addition, the emission of 1 has also been quenched by 4-nitroaniline (4-NA) in methanol-aqueous solution, a precursor to nitroaromatic dyes, even in the existence of other nitroaromatic compounds (ten NACs) and the LOD and K sv are 0.0272 µM and 5.04 × 10 5 M⁻¹ respectively. The quenching has been explained by the FRET and PET pathway. The presence of free phenolic-OH of HSSA²⁻ within the network may assist to invite selectively the analyte (Al 3+ and 4-NA) which may facilitate dissociation, promote energy transfer and contribute to the quenching effect. The compound, 1 , shows band gap 3.20 eV (theoretical, 3.31 eV) and may serve as semiconductor to fabricate Schottky diode device. The thin film of 1 was used to measure the electrical conductivity, 2.01 × 10⁻⁶ Sm⁻¹ at ambient condition which has been improved by light irradiation to 5.62 × 10⁻⁶ Sm⁻¹. Thus, stimulation by light underscores the possibility of this material for dual sensing applications and Schottky diode behaviour.