Three Cd(II) MOFs with Different Functional Groups: Selective CO₂ Capture and Metal Ions Detection

Abstract

Three Cd(II) iso-frameworks {[Cd(BIPA)(IPA)]·DMF} (1), {[Cd(BIPA)(HIPA)]·DMF} (2), and {[Cd(BIPA)(NIPA)]·2HO} (3) were synthesized from the self-assembly of the BIPA ligand (BIPA = bis(4-(1 H-imidazol-1-yl)phenyl)amine) and different carboxylic ligands (HIPA = isophthalic acid, HHIPA = 5-hydroxyisophthalic acid, HNIPA = 5-nitroisophthalic acid) with Cd(II), which have amino groups, amino and phenolic hydroxyl groups, and amino and nitro groups, respectively. Both 1 and 2 exhibit CO uptakes of more than 20 wt %, indicating that amino and phenolic hydroxyl functionalized groups are beneficial to CO adsorption. Their applications and mechanisms in detecting metal ions were researched. The results exhibit that 1 and 2 are dual-responsive photoluminescent sensors for Hg and Pb ions with low detection concentration and high quenching constant. Besides, like most MOFs, 3 can detect a trace quantity of Fe and Cu.

A Bifunctional Luminescent Metal–Organic Framework for the Sensing of Paraquat and Fe3+ Ions in Water

“…f) 3D framework of compound 1 alongt he a axis. g) Schematic representation of the (3,3,4,4)-connected topology in compound 1.…”

“…[1] On the other hand, Fe 3+ + ions play an important role in severalb iological processes, such as oxygen metabolism, oxygen transport, and electron transfer.H owever, insuffi-cient or excessive amountso fF e 3+ + ions may affect metabolism and cell homeostasis, and can even lead to physical illnesses, such as anemia, skin diseases,d iabetes, Alzheimer'sd isease, and Parkinson'sd iseases. [2,3] Av ariety of traditional methods have been used to efficiently ands ensitively monitor pesticide and metal-ion levels, including gas chromatography,L C-MS, gel-permeationc hromatography,i nductively coupled plasmaatomic emission spectrometry,a nd atomic absorption spectrophotometry.N evertheless, these methods often require expensive equipment, cumbersome preprocessing, and strict operating techniques. [4] Therefore, the exploration of suitable methods for the facile and sensitive detection of pesticides and heavy metal ions, including Fe 3+ + ,i sh ighly important.…”

“…As one of the most well-known porousm aterials, metal-organic frameworks (MOFs) have drawn widespread attention, not only because of their diversea nd interesting architectures, but also because they have shown great potentiali nt he fields of gas separation, heterogeneous catalysis, molecular magnetism, and chemical sensing. [5][6][7][8][9][10][11][12][13][14] In particular,o ver the past decade, luminescent MOFs have been regardeda sp romising candidate materials, owing to their competitive advantages compared with other fluorescentm aterials: [2][3][4][10][11][12][13][14] 1) the good crystallinity of MOFs allows them to adopt defined structures that can be characterized by using single-crystal X-ray diffraction, which is beneficial for establishing structure-property correlations and, thus, for exploring their luminescence-response mechanisms;2 )their structures can be readily adjusted and modified by regulating their two major components,t hat is, their metal centers and organic linkers, as well as by tuning other reaction parameters, including the solvent, temperature, pH value, and the relative proportions of the reagents,t hereby affording the opportunity to realize structure-inducedl uminescence performance;3 )most importantly,t he adjustable porosity of MOFs allow them to adsorb and pre-enrich target analytes, which can increase the probability of interactions between host MOFs and guest analytes,t hereby enhancing their detection limit and sensitivity.T hus,alarge number of MOFbased luminescent sensors have been prepared and used in the detection of differenta nalytes, including biomolecules, explosives, organic molecules, anions,c ations, temperature, and pH value. [2][3][4][10][11][12][13][14] Nevertheless, most of the previously reported MOF-based sensors have been used in nonaqueous system, which may be mainly owing to the poor water stabilityo f MOFs.…”

“…In addition, to date, very few reports have been devoted to the coordination chemistryo ft he Hcptpyligand. [15] Based on these considerations,h erein, we report the synthesis, crystal structure, and luminescence properties of a3 D (3,3,4,4)-connected topological MOF that contained two different ligands: [Zn 2 (cptpy)(btc)(H 2 O)] n (1;H cptpy = 4-(4-carboxyphenyl)-2,2':4',4"-terpyridine, H 3 btc = 1,3,5-benzenetricarboxylic acid). MOF 1 was obtained from the reaction of Zn 2+ + ions with Hcptpya nd H 3 btc in aw ater/MeCNm ixed solvents ystem under hydrothermal conditions, and wasc arefully characterized by using ar ange of different methods, including singlecrystal X-ray diffraction (SXRD), IR spectroscopy,p owder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA).…”

“…Structural analysisi ndicated that the asymmetric unit of compound 1 contained two independentZ n 2+ + ions, one cptpy À ligand, one btc 3À ligand,a nd one coordinated water molecule. Two types of Zn 2+ + ions were alternatelyb ridged by cptpy À and btc 3À ligands to generate a3 Df ramework with an ew (3,3,4,4)connected topology.L uminescencer esults suggestt hat compound 1 could act as ab ifunctional sensor for the detectiono f paraquat (PAQ) and Fe 3+ + ions, based on af luorescencequenching effect. Importantly,M OF 1 displayed remarkable stabilityt owards air and water:t he skeleton of compound 1 was stable in air for more than 3months and in aqueous solutions (pH [3][4][5][6][7][8][9][10][11] for at least 1week.…”