New Cyanostyrylcopillar[5]arene Derivative: Synthesis, Photophysical Study, Chromogenic Detection of Aliphatic Amines, and Biofilm–Antibiofilm Activity

The synthesis, characterization, and application of a
new cyanostyrylcopillar[5]arene 1 is reported. Single-crystal
X-ray diffraction and other
spectroscopic techniques confirm the identity of the new copillar 1. The X-ray diffraction study reveals that the copillar 1 exhibits a 1D supramolecular chain in the solid state involving
π···π interactions along the crystallographic c-axis and 1D chains are further connected by interchain
C–H···π interactions to establish 2D supramolecular
layers within the crystallographic bc-plane. 2D supramolecular
chains on further packing introduce a 3D structure with void spaces
filled with hexane molecules. Through minimal deviation in the dihedral
angle, the cyano-substituted ethylenic group in 1 shows
a conjugation with the phenolic –OH, favoring intramolecular
bond conjugation (ITBC) and colorimetrically detects the aliphatic
amines over aromatic amines in CH3CN. Among the aliphatic
amines, tertiary amines are differentiated from primary and secondary
amines by the naked eye through color change. Both in solution and
solid states, 1 displays vapor phase detection of volatile
aliphatic amines. Antibacterial activity analysis shows that while 1 exhibits the antibiofilm action against Gram-positive pathogenic
bacteria, Staphylococcus aureus, it
promotes biofilm formation by Gram-negative pathogenic bacteria, Pseudomonas aeruginosa.