Functionalization of Microporous Lanthanide-Based Metal–Organic Frameworks by Dicarboxylate Ligands with Methyl-Substituted Thieno[2,3-b]thiophene Groups: Sensing Activities and Magnetic Properties

Abstract

From a methyl-substituted thieno[2,3-b]thiophene dicarboxylate, three types of three-dimensional (3-D) microporous lanthanide-based metal-organic frameworks, {[Ln(DMTDC)1.5(H2O)2]·DEF}n (type I, Ln = Eu 1, Tb 2), {[Ln(DMTDC)1.5(H2O)2]·0.5DMF·0.5H2O}n (type II, Ln = Gd 3, Dy 4, Er 5), and {[Ln4(DMTDC)6(DMF)2]·0.5DMF·1.5H2O}n (type III, Ln = Er 6) (H2DMTDC = 3,4-dimethylthieno[2,3-b]thiophene-2,5-dicarboxylic acid, DEF = N,N'-diethylformamide, DMF = N,N'-dimethylformamide), have been solventhermally synthesized. Types I and II are isostructural, which exhibit 1-D triangular channels constructed by double-stranded rod-shaped {Ln(CO2)2}n chains. Type III demonstrates an intriguing framework with triple-stranded rod-shaped {Ln(CO2)3}n chains arranged along the (1,1,0) and (1,-1,0) axes and possesses two kinds of triangular channels along two axes, respectively. Immobilization of the Lewis basic sites of thiophene groups induced gas adsorption and sensing properties into these microporous frameworks. Complexes 5(Er) and 6(Er) display moderate adsorption properties toward N2 and CO2, and the Qst of CO2 are as high as 36.3 and 34.8 kJ mol(-1), respectively. Complexes 1(Eu) and 2(Tb) exhibit sensing properties toward nitrobenzene, acetone, and the Cu(2+) ion in both DMF and aqueous solution. Complex 3(Gd) shows a significant magnetocaloric effect with ΔSm = 24.3 J·kg(-1)·K(-1) at 3.0 K and 7 T. Complex 4(Dy) exhibits slow magnetic relaxation with the energy barrier Δ/kB of 48.29 K.

Selective detection of trinitrophenol by a Cd(ii)-based coordination compound

“…The chemistry of such materials is of great interest to synthetic chemists because of their intriguing structural motifs as well as potential applications in areas such as catalysis, magnetism, ion exchange, drug delivery, conductance, photoluminescence and chemical sensing. [4][5][6][7][8][9][10][11][12][13][14][15] In addition to the direct role of the metal ions and organic ligands, there are many more essential conditions, including counter anions, reaction temperatures, solvent media, external stimuli, and pH of the reaction medium, which play crucial roles during compound formation. In addition, there is an eternal relationship among the structure, property and application of the compounds.…”

Synthesis and structural characterisation of the copper MOF: STAM-NMe2

“…Metal-organic frameworks (MOFs) are of great interest in the fields of biomedicine, [1][2][3] catalysis, 4 sensing, 5 luminescence, 6,7 separation, 8 gas adsorption and release, [9][10][11][12] and have recently been highlighted as promising materials in the field of air purification. [13][14][15][16] MOFs have received attention in these areas due to their high porosities, 17,18 resistance to residual and coordinated solvent loss, 19,20 and consequently the availability of coordinatively unsaturated sites (CUS) for the adsorption of guest molecules.…”

Engineered Bifunctional Luminescent Pillared‐Layer Frameworks for Adsorption of CO2 and Sensitive Detection of Nitrobenzene in Aqueous Media

“…This provides clear evidence to rule out the long‐range resonance energy‐transfer process from the fluorophores of MOFs 1 – 5 to the nonemissive NB analyte [72] . Furthermore, the wavelength of irradiation light at λ =350 nm indicates the negligible probability of competitive absorption for the quenching responses [73] . However, there is a preliminary consensus that the quenching effect can be mostly ascribed to the donor–acceptor electron‐transfer mechanism [10, 13, 73–75] .…”

“…Furthermore, the wavelength of irradiation light at λ =350 nm indicates the negligible probability of competitive absorption for the quenching responses [73] . However, there is a preliminary consensus that the quenching effect can be mostly ascribed to the donor–acceptor electron‐transfer mechanism [10, 13, 73–75] . Because a nitro group is a typical electron‐withdrawing substituent and stabilizes the LUMO of the aromatic analyte through conjugation, [75] NB is therefore highly electron deficient in nature and generally has a LUMO lying at a lower energy than that of the conduction band of a MOF [9] .…”