Two PbII-based coordination polymers based on 5-aminonicotinic acid and 5-hydroxynicotinic acid for Knoevenagel condensation reaction and luminescent sensor

Two new Pb^II-based coordination polymers based on 5-aminonicotinic acid (namely HL–NH₂) and 5-hydroxynicotinic acid (namely HL–OH) are both successfully synthesized under solvothermal synthesis conditions. PbCl₂ and HL-NH₂ can generate a 3D network with the formula of {[Pb₃(L-NH₂)₂Cl₅]·(H₂O)}_n (complex 1). The –NH₂ functional group is replaced by –OH on the organic linker to further coordinate with Pb^II to fabricate another 3D framework of [Pb₂(L–O)Cl₂]_n (complex 2). Interestingly, various and fanatics structures can be tuned and regulated by different functional substituent groups. Furthermore, complex 1 can be applied as a high-efficient heterogeneous catalysis for Knoevenagel condensation reaction. Meanwhile, complex 2 is an excellent potential luminescent sensor for Fe³⁺.