Sonochemical synthesis of microscale Zn(II)-MOF with dual Lewis basic sites for fluorescent turn-on detection of Al3+ and methanol with low detection limits

The effects of synthetic methods, modulator types, content of modulator, and reaction time on the size and morphology of a microscale Zn-MOF containing dual Lewis basic amino and carbonyl groups, namely [Zn(NH2-bdc)(4,4’-bpy)] {NH2-H2bdc = 2-amino-1,4-benzenedicarboxylic acid and bpy = 4,4’-bypyridine} were systemically investigated. The uniform octahedral microparticles of Zn-MOF with an average size of 1.7 µm were obtained within an hour at ambient temperature under the ultrasound irradiation using sodium acetate as a modulating agent. Interestingly, Zn-MOF has demonstrated as a dual-functional fluorescent detection of Al3+ and methanol based on fluorescent turn-on strategy. Very low detection limits (LODs) for Al3+ and methanol by using microcrystalline Zn-MOF reaches at 30 nM and 0.7% (v/v), respectively. With the comparison to the larger size of polycrystalline Zn-MOF, the microparticles obtained from an ultrasonic route exhibit the improvement of the detection sensitivity. The dual uncoordinated Lewis basic sites play an important role in the sensitivity and selectivity of the detection. Additionally, the fluorogenic change in the sensing process can be noticed by naked eye under UV-light allowing the preliminary on-field screening.