Cross-dehydrogenative coupling (CDC) efficiently constructs complex organic molecules by directly coupling two C-H bonds from different substrates. This enables the functionalisation of existing chromophores with different substituents, facilitating efficient sensor development. Electronically diverse C-3 sulfenylated 2-phenyl-4H-pyrido[1,2-a]pyrimidin-4-ones (3a-3d) were synthesised using iodine mediated CDC protocol and structurally characterised using FT-IR, ¹H and ¹³C NMR and mass spectrometry technique. Single Crystal X-ray crystallography was utilised for establishing the molecular structure of 3d. The absorption and emission intensity for all the synthetics were recorded in the range of 365-375 and 406-509 nm, respectively in solvents of varying polarity. Compound 3b, with distinct dispersion of the frontier molecular orbitals due to ring extension, showed exceptional absorption and emission intensity in water and methanol. All the sensing applications of 3b were investigated using water/methanol (1:4; v/v) as the solvent system. An abrupt increase in absorption intensity with a decrease in emission maxima of 3b was observed upon Fe(NO₃)₃.9H₂O addition. A detection limit of 1.27 * 10⁻⁶ M, low response time and thermal stability served as some of the characteristic features which established the probe as a potential sensor for Fe³⁺ ion. Further, the stoichiometry and binding constant of the complex was determined by Benesi-Hildebrand and jobs plot.

交叉脱氢偶联 (CDC) 通过直接偶联来自不同底物的两个 CH 键，有效构建复杂的有机分子。这使得现有发色团能够具有不同取代基的功能化，从而促进高效的传感器开发。使用碘介导的 CDC 方案合成电子多样化的 C-3 磺基化 2-苯基-4 H -吡啶并[1,2- a ]嘧啶-4-酮(3a-3d)，并使用 FT-IR、¹ H 和¹³进行结构表征13C NMR 和质谱技术。单晶X射线晶体学用于建立3d的分子结构。在不同极性的溶剂中，所有合成物的吸收和发射强度分别在 365-375 和 406-509 nm 范围内记录。化合物3b由于环延伸而具有明显的前沿分子轨道分散，在水和甲醇中表现出异常的吸收和发射强度。3b的所有传感应用均使用水/甲醇（1:4； v/v）作为溶剂系统进行研究。_{添加Fe(NO 3} ) ₃ .9H ₂ O后，观察到吸收强度突然增加，而3b的发射最大值降低。^{1.27 * 10 -6} M的检测限、低响应时间和热稳定性是该探针作为Fe ³⁺离子的潜在传感器的一些特征。此外，复合物的化学计量和结合常数由 Benesi-Hildebrand 和工作图确定。