Instant high-selectivity Cd-MOF chemosensor for naked-eye detection of Cu( ii ) confirmed using in situ microcalorimetry

• Published in: Green chemistry : an international journal and green chemistry resource : GC Vol. 18; no. 4; pp. 951 - 956
• Main Authors: Qiao, Chengfang, Qu, Xiaoni, Yang, Qi, Wei, Qing, Xie, Gang, Chen, Sanping, Yang, Desuo
• Format: Journal Article
• Language: English
• Published: 01.01.2016
• Subjects: Channels; Chemoreceptors; Color; Crystal structure; Eyes; Methyl alcohol; Three dimensional; Transformations
• ISSN: 1463-9262; 1463-9270
• DOI: 10.1039/c5gc02393a

A Cd(ii) metal-organic framework, {NH sub(2)(CH sub(3)) sub(2 ).Cd sub(2.5)(L) sub(2)(H sub(2)O).(H sub(2)O)}n (1; H sub(3)L = tricarboxytriphenylamine), has been synthesized and features a 3D microporous framework with two different types of 1D channel. Addition of Cu super(2+) to crystals of 1 instantly leads to a clear color change from yellow to dark green crystalline samples (2), which are structurally identified as {NH sub(2)(CH sub(3)) sub(2 2).Cd sub(3)Cu sub(2)(L) sub(4)(H sub(2)O) sub(2).(H sub(2)O) sub(2)}n. In situ microcalorimetry shows that the response time of 1 to a Cu super(2+) concentration of 10 super(-4) mol L super(-1) is as short as 9 s. Naturally, MOF 1 could potentially be used for the naked eye detection of Cu super(2+) ions in real-world applications. In addition, in situ microcalorimetry is successfully employed to real-time record a SC-SC guest transformation, where the guest water molecules can be selectively exchanged by methanol or N, N-dimethylacetamide (DMA) molecules (1.CH sub(3)OH and 1.DMA), and the molar enthalpies, Delta H super([thetas]) sub(m), are quantitatively determined as being (-71.34 plus or minus 0.52) and (-87.13 plus or minus 0.86) kJ mol super(-1), respectively. This is the first report where the processes of SC-SC transformation and detection of Cu super(2+) are objectively presented.