Luminescent Turn-On/Turn-Off Sensing Properties of a Water-Stable Cobalt-Based Coordination Polymer

Abstract

Using a pyridine-derived molecule 1,3,5-tris­(4-pyridyl)­benzene (TPB) and a polycarboxylate linker 1,3-benzenedicarboxylic acid (H2BDC), a Co­(II)-based coordination polymer {[Co­(TPB)­(BDC)]·0.5H2O} (1) with a high water stability was successfully prepared and fully characterized. Compound 1 possesses a unique 3D pillar-chained network wherein the adjacent 1D double [Co­(BDC)] chains are further connected by TPB pillars. The photoluminescence property of 1 was studied, exhibiting a weak emission with UV light irradiation. Interestingly, the multiresponsive luminescence makes compound 1 a versatile chemosensor for several metal cations and inorganic anions in aqueous solutions. It has a great ability to selectively detect cationic Al3+ and Cu2+ and anionic IO4 – through luminescence turn-on or turn-off effects. In particular, the luminescence intensity could be significantly decreased by existence of IO4 –, which is seldom reported among the cobalt-based coordination polymers and implies that 1 can act as an effective fluorescence probe to sense corresponding species. The quenching mechanism for various ions has been discussed in detail. In addition, the magnetic property of 1 was investigated.

Recent progress in polyoxometalate–viologen photochromic hybrids: structural design, photochromic mechanism, and applications

“…Photochromic materials with reversible color changes have received tremendous scientific attention for smart windows, molecular switching, data storage, anticounterfeiting and so on. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Polyoxometalates (POMs) are a class of very important photochromic materials due to their good redox properties and photoactivity, and readily undergo photoinduced electron transfer to form Mo/W(V)-containing heteropolyblue. [16][17][18][19][20][21][22][23][24][25][26][27][28][29] In general, purely inorganic POMs have poor photochromic behavior and are difficult to synthesize, while purely organic photochromic materials have poor fatigue resistance and high temperature resistance despite their fast response and rich color, 30,31 so it has been difficult to find new photochromic materials in pure organic or inorganic systems.…”

Four Novel Cobalt(II) Coordination Polymers Based on Anthracene-Derived Dicarboxylic Acid as Multi-functional Fluorescent Sensors toward Different Inorganic Ions

“…Among them, the investigation on cobalt CP-based fluorescent chemosensors is still in its infancy. Cobalt ions normally have a low emission performance due to their non-d electron configuration; however, when ligating to conjugated organic molecules, the Co-CPs would also give a luminescent performance under ultraviolet light irradiation . For example, Cui et al designed a cobalt framework (ZJU-109) using mixed organic ligands, which served as the fluorescence turn-on sensor for recognizing Fe 3+ with a low detection limit .…”

A multi-responsive luminescent Co(ii) coordination polymer assembled from amide-functionalized organic units for effective pH and cation sensing

“…In fact, though cobalt ions with a non d 10 electron configuration usually have a low emission performance, once ligated to conjugated organic molecules some Co-MOFs may also have a light-emitting performance and show a turn-on effect under UV light irradiation. [35][36][37][38] Meanwhile, REE-based luminescent MOF materials, especially Eu and Tb, are also widely explored owing to the characteristic emission, high quantum efficiency and long lifetime. 39 Except for the detection of REE ions, MOFs based on transition metals could also be post-modified to enhance the detection selectivity and sensitivity.…”