ABSTRACT
The field of metal-organic framework (MOF)-based biomimetic catalysts has achieved great progress but is still in its infancy. The systematic investigation of the tailored construction of MOF-based biomimetic catalysts is required for further development. Herein, two iron-based MOFs, namely, [(Fe3O)2(H2O)4(HCOO)(L)2]n (HUST-5: H6L = hexakis(4-formylphenoxy) cyclotriphosphazene; HUST = Huazhong University of Science and Technology) and [(Fe3O)(H2O)3(L)]n (HUST-7) have been fabricated through the assembly of different iron clusters and hexa-carboxylate ligand under the control of the added acid species. The two MOFs exhibit distinct secondary building units (SBUs) and topological structures, which could be used as biomimetic catalysts for the systematic comparisons of structural characteristics and the catalytic activity. Both MOFs possess catalytic activity similar to that of natural peroxidases towards the catalysis of the oxidation of a variety of substrates. Significantly, HUST-5 and HUST-7 can effectively catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 accompanied by significant colorimetric biosensing. With same compositions, different catalytic performances were obtained due to differences in the porous structures and characteristics of SBUs in two Fe-MOFs, which was also validated by theoretical calculation results. Furthermore, the phenomenon of colorimetric biosensing could be significantly suppressed by the addition of ascorbic acid (AA) during the oxidation process of TMB. It was observed from these findings that a facile colorimetric biosensing platform for detecting H2O2 and ascorbic acid has been successfully explored. Therefore, this work provides another unique perspective for the tailor-made preparation of stable MOF-based peroxidase mimics with excellent catalytic performance and colorimetric biosensing.
Subject(s)
Biomimetic Materials/chemistry , Biosensing Techniques , Colorimetry , Iron/chemistry , Metal-Organic Frameworks/chemistry , Catalysis , Molecular Structure , Oxidation-Reduction , Particle Size , Peroxidase/metabolism , Porosity , Surface PropertiesABSTRACT
Due to the structural advantages displayed by Metal-Organic Frameworks (MOFs), integrating Valence Tautomerism (VT) systems within MOFs could be an effective strategy in order to break through the constraints of the traditional ones. Herein, we report the first successful integration of a VT system into a MOF termed VT-MOF-1. The structural characteristics of VT-MOF-1, such as dinuclear cobalt-catechol clusters and solvent-accessible pores, are both innovative and novel, potentially yielding new vitality within VT field. In addition, VT-MOF-1 exhibits specific behaviors responsive to temperature and different solvent molecules as n-butanol, tert-butanol, and isopropyl alcohol. The entropy values and configurations of the solvent molecules might be responsible for the tunable sensing behaviors.
ABSTRACT
Herein, we report the construction of a neutral, radical-rich, cobalt valence tautomeric triangle, which consists of two types of radical groups including tetrazine-based bridges and semiquinone anions at high temperature and has traits of high intensity and density of sensing sites. The mechanism of the Valence Tautomerism process within the triangle has been illustrated as one electron transfer, preceding a two electrons transfer along with the phenomenon of spin flipping.
ABSTRACT
Two 3D lanthanide frameworks, [Ln7(DPA)5(NA)3(µ3-OH)8(H2O)3]·2.5H2O [H2DPA = diphenic acid; HNA = nicotinic acid; Ln = Gd (1), Dy (2)], were synthesized and structurally characterized. They were rarely seen examples of 3D frameworks constructed from heptanuclear trigonal-antiprismatic lanthanide clusters with mixed H2DPA and HNA ligands. Both 1 and 2 show typical antiferromagnetic interactions. Additionally, complex 1 possesses a large magnetocaloric effect of 34.15 J kg(-1) K(-1).
ABSTRACT
In the title compound, C(10)H(11)NO(2)S, the acetyl-acetone group crystallizes in the keto form with all the non-hydrogen atoms in the acetyl-acetone group approximately co-planar with a maximum atomic deviation 0.055â (2)â Å; the dihedral angle between the acetyl-acetone group and the pyridine ring is 85.90â (6)°. An intra-molecular O-Hâ¯O hydrogen bond involving the acetyl-acetone group forms a six-membered ring.
ABSTRACT
In the title centrosymmetric Mg(II) complex, [Mg(2)(C(7)H(3)NO(4))(2)(H(2)O)(6)], each Mg cation is N,O-chelated by a pyridine-2,4-dicarboxyl-ate dianion and is coordinated by three water mol-ecules. A carboxyl-ate O atom from the neighboring pyridine-2,4-dicarboxyl-ate dianion bridges the Mg cation to complete the MgNO(5) distorted octa-hedral coordination geometry. The dinuclear complex mol-ecules are linked by inter-molecular O-Hâ¯O hydrogen bonding, forming a three-dimensional supra-molecular structure.
