Recent advances in enzyme immobilization techniques: Metal-organic frameworks as novel substrates

Mehta, J.,Bhardwaj, N.,Bhardwaj, S.K.,Kim, K.H.,Deep, A. Elsevier Publishing Company 2016 Coordination chemistry reviews Vol.322 No.-

<P>In the past few years, metal organic frameworks (MOFs) have drawn increasing research interest as bioimmobilization support materials. The unique properties of MOFs, including tunable porosity, desirable functionality, extremely high surface area, and chemical/thermal stability, have motivated a considerable interest in exploiting them as a potential matrix for enzyme immobilization. Improvements in the biocatalyst efficiency, promising recyclability, enhanced accessibility to active sites, and a high loading capacity are the main features of the novel MOF-enzyme supports. This review aims to cover the recent progress in the application of MOFs as enzyme immobilization supports. We discuss different approaches used in the development of MOF-enzyme biocatalytic supports, such as surface adsorption, diffusion, and in-situ encapsulation. The trends in current developments and the significance of each strategy are critically reviewed in this paper. (C) 2016 Elsevier B.V. All rights reserved.</P>

Influences of metal, non-metal precursors, and substrates on atomic layer deposition processes for the growth of selected functional electronic materials

Lee, S.W.,Choi, B.J.,Eom, T.,Han, J.H.,Kim, S.K.,Song, S.J.,Lee, W.,Hwang, C.S. Elsevier Publishing Company 2013 Coordination chemistry reviews Vol.257 No.23

Atomic layer deposition (ALD) is known for its self-limiting reaction, which offers atomic-level controllability of the growth of thin films for a wide range of applications. The self-limiting mechanism leads to very useful properties, such as excellent uniformity over a large area and superior conformality on complex structures. These unique features of ALD provide promising opportunities for future electronics. Though the ALD of Al<SUB>2</SUB>O<SUB>3</SUB> film (using trimethyl-aluminum and water as a metal precursor and oxygen source, respectively) can be regarded as a representative example of an ideal ALD based on the completely self-limiting reaction, there are many cases deviating from the ideal ALD reaction in recently developed ALD processes. The nonconventional aspects of the ALD reactions may strongly influence the various properties of the functional materials grown by ALD, and the lack of comprehension of these aspects has made ALD difficult to control. In this respect, several dominant factors that complicate ALD reactions, including the types of metal precursors, non-metal precursors (oxygen sources or reducing agents), and substrates, are discussed in this review. The examination of such aspects may contribute to the further understanding of non-ideal ALD reactions. Several functional materials for future electronics, such as higher-k dielectrics (TiO<SUB>2</SUB>, SrTiO<SUB>3</SUB>), phase change materials (Ge-Sb-Te solid solution), noble metal electrodes (Ru, RuO<SUB>2</SUB>), and resistive switching materials (NiO), are addressed in this review. Finally, desirable directions of ALD are suggested with consideration of the uncommon and non-ideal aspects of the ALD reactions.

Metallacycles derived from metal complexes of exo-coordinated macrocyclic ligands

Lee, E.,Lee, S.Y.,Lindoy, L.F.,Lee, S.S. Elsevier Publishing Company 2013 Coordination chemistry reviews Vol.257 No.21

The assembly of metallacyclic structures incorporating exo-coordinated macrocyclic ligand components is reviewed. The exo-coordination approach provides a means for building extended cyclic assemblies and contrasts with the use of conventional endocyclic macrocyclic coordination which generally results in metal-in-cavity products. The approach, which depends on the availability of one or more donor atoms bearing electron lone pairs that are oriented exo to their macrocyclic cavity, has been employed to produce a range of diverse metallacyclic structures; examples of such metallo-assemblies displaying cyclic dimeric, trimeric, tetrameric, and hexameric topologies are presented.

Electron-transfer properties of high-valent metal-oxo complexes

Elsevier Publishing Company 2013 Coordination chemistry reviews Vol.257 No.9

Electron-transfer properties of heme and non-heme high-valent metal-oxo complexes are overviewed in relation to their reactivity toward oxidation of substrates. The rate constants of electron transfer from a series of electron donors to various heme and non-heme high-valent metal-oxo complexes such as compound I and compound II of horseradish peroxidase (HRP), (TMP)Mn<SUP>IV</SUP>(O) ((TMP=tetramesityl-porphyrinate dianion), (TBP<SUB>8</SUB>Cz)Mn<SUP>V</SUP>(O) (TBP<SUB>8</SUB>Cz=octa-tert-butylphenylcorrolazinate trianion) and [(L)Fe<SUP>IV</SUP>(O)]<SUP>2+</SUP>, where L=TMC, 1,4,8,11-tetra-methyl-1,4,8,11-tetraazacyclotetradecane; Bn-TPEN, N-benzyl-N,N',N'-tris(2-pyridylmethyl)ethane-1,2-diamine; N4Py, N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine; bisp, 3,7-diazabicyclo[3.3.1]nonane) were evaluated in light of the Marcus theory of electron transfer in order to determine the reorganization energy (λ) for electron transfer. The λ value increases in the order: 1.3eV (compound I of HRP), 1.53eV [(TBP<SUB>8</SUB>Cz)Mn<SUP>V</SUP>(O)], 1.6eV (compound II of HRP), 1.7eV [(TMP)Mn<SUP>IV</SUP>(O)], 2.05eV [(bisp)Fe<SUP>IV</SUP>(O)]<SUP>2+</SUP>, 2.37eV [(TMC)Fe<SUP>IV</SUP>(O)]<SUP>2+</SUP>), 2.55eV ([(Bn-TPEN)Fe<SUP>IV</SUP>(O)]<SUP>2+</SUP>), 2.74eV ([(N4Py)Fe<SUP>IV</SUP>(O)]<SUP>2+</SUP>). The λ value of compound I of HRP is the smallest among those of high-valent metal-oxo complexes, because the site of the reduction is on the porphyrin ligand, whereas the site of the reduction is on the metal for the other high-valent metal-oxo complexes. The λ values of high-valent metal-oxo porphyrins are generally smaller than those of non-heme iron(IV)-oxo complexes. The effects of Lewis acidic metal ions and Bronsted acids on the one-electron reduction of high-valent metal-oxo complexes are also overviewed in relation to their enhancement of the oxidizing ability towards reductants.

Transition and post-transition metal ion chemistry of dibenzo-substituted, mixed-donor macrocycles incorporating five donor atoms

Lindoy, L.F.,Meehan, G.V.,Vasilescu, I.M.,Kim, H.J.,Lee, J.E.,Lee, S.S. Elsevier Publishing Company 2010 Coordination chemistry reviews Vol.254 No.15

The transition and post-transition metal ion chemistry of a wide range of potentially pentadentate dibenzo-substituted macrocyclic ligands incorporating nitrogen, oxygen and/or sulfur donors is reviewed and shown to result in a diverse range of structural types. Aspects of metal ion recognition, bulk membrane transport, systems incorporating appended chromophores, a sulfate binding system, induced Cu(I)/Cu(II) redox switching, coordination polymers, and unsymmetric macrocyclic ligand systems are all discussed.

The development of light-responsive, organic dye based, supramolecular nanosystems for enhanced anticancer therapy

Cheng, Hong-Bo,Cui, Yixin,Wang, Rui,Kwon, Nahyun,Yoon, Juyoung Elsevier Publishing Company 2019 Coordination Chemistry Reviews Vol. No.

<P><B>Abstract</B></P> <P>Light-responsive supramolecular nanosystems refer to phototherapeutic agents that could be triggered by light. They have thus shown promising applications and aroused tremendous attention in many fields including drug delivery systems, photodynamic therapy and photothermal therapy. In the review, after a brief introduction of the development of light-responsive organic dye based supramolecular nanosystems for anticancer therapy, an overview of recent advances made during the past five years is provided. Finally, challenges that need to be confronted and new opportunities that exist in the rapidly developing field are discussed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The recent advances in the development of light-driven turn on cancer-associated supramolecular theragnostic are reviewed. </LI> <LI> Types and characteristics of light-responsive supramolecular nanosystems for anticancer therapy are discussed. </LI> <LI> The main approaches to the constructing of light-responsive supramolecular nanosystems for anticancer therapy are included. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Catalytic Pauson-Khand-type reactions and related carbonylative cycloaddition reactions

Park, J.H.,Chang, K.M.,Chung, Y.K. Elsevier Publishing Company 2009 Coordination Chemistry Reviews Vol. No.

The development of a heterogeneous catalytic Pauson-Khand reaction and cobalt carbonyl-catalyzed tandem carbonylative cycloaddition reaction of unsaturated hydrocarbons studied in our laboratory are reviewed.

Lanthanide luminescence efficiency in eight- and nine-coordinate complexes: Role of the radiative lifetime

Bunzli, J.C.G.,Chauvin, A.S.,Kim, H.K.,Deiters, E.,Eliseeva, S.V. Elsevier Publishing Company 2010 Coordination Chemistry Reviews Vol. No.

The photophysical parameters for the sensitization of metal-centred luminescence are analyzed in two series of complexes with tridentate and hexadentate ligands having N<SUB>x</SUB>O<SUB>y</SUB> chelating units. In particular, the radiative lifetime τ<SUB>rad</SUB> is experimentally estimated for 29 nine-coordinate Eu<SUP>III</SUP> complexes and 10 eight- and nine-coordinate Yb<SUP>III</SUP> complexes. The known dependence of τ<SUB>rad</SUB> on refractive index is substantiated by comparing data for solid-state samples and solutions. Moreover, a clear dependence of τ<SUB>rad</SUB> with the coordination environment is evidenced and in the case of Eu<SUP>III</SUP>, a comparison between τ<SUB>rad</SUB> and the nephelauxetic effect generated by the ligands is attempted. Altogether, this extensive analysis points to the importance of having a handle on τ<SUB>rad</SUB> when designing ligands for highly luminescent lanthanide-containing molecular edifices. This, in turn, should stimulate initiating theoretical considerations to unravel a reliable relationship between τ<SUB>rad</SUB> and the electronic structure of the ligands.

Intrinsic properties and reactivities of mononuclear nonheme iron-oxygen complexes bearing the tetramethylcyclam ligand

de Visser, S.P.,Rohde, J.U.,Lee, Y.M.,Cho, J.,Nam, W. Elsevier Publishing Company 2013 Coordination chemistry reviews Vol.257 No.2

Iron-oxygen species, such as iron(IV)-oxo, iron(III)-superoxo, iron(III)-peroxo, and iron(III)-hydroperoxo complexes, are key intermediates often detected in the catalytic cycles of dioxygen activation by heme and nonheme iron enzymes. Our understanding of the chemistry of these key intermediates has improved greatly by studies of the structural and spectroscopic properties and reactivities of their synthetic analogues. One class of biomimetic coordination complexes that has proven to be particularly versatile in studying dioxygen activation by metal complexes is comprised of Fe<SUP>IV</SUP>?O and Fe<SUP>III</SUP>?O<SUB>2</SUB>(H) complexes of the macrocyclic tetramethylcyclam ligand (TMC, 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane). Several recent advances have been made in the synthesis and isolation of new iron-oxygen complexes of this ligand, their structural and spectroscopic characterization, and elucidation of their reactivities in various oxidation reactions. In this review, we summarize the chemistry of the first structurally characterized mononuclear nonheme iron(IV)-oxo complex, in which the Fe<SUP>IV</SUP>?O group was stabilized by the TMC ligand. Complexes with different axial ligands, [Fe<SUP>IV</SUP>(O)(TMC)(X)]<SUP>n+</SUP>, and complexes of other cyclam ligands are discussed as well. Very recently, significant progress has also been reported in the area of other iron-oxygen intermediates, such as iron(III)-superoxo, iron(III)-peroxo, and iron(III)-hydroperoxo complexes bearing the TMC ligand. The present results demonstrate how synthetic and mechanistic developments in biomimetic research can advance our understanding of dioxygen activation occurring in mononuclear nonheme iron enzymes.

Synthesis of metal-organic frameworks (MOFs) with microwave or ultrasound: Rapid reaction, phase-selectivity, and size reduction

Khan, N.A.,Jhung, S.H. Elsevier Publishing Company 2015 Coordination chemistry reviews Vol.285 No.-

Microwave (MW) and ultrasonic (US) irradiation are the most simple, inexpensive, and efficient nonconventional heating methods available in applied chemistry. Both techniques are well established in the field of organic transformations/syntheses, even though the utilization of alternative methods in the synthesis of emerging materials, including inorganic nanomaterials, nanoporous materials, and hybrid materials, is rapidly materializing. The rapidly growing number of publications regarding the synthesis of such materials via MW and US irradiation clearly suggests that these techniques will play a role in materials chemistry. In this review, we have given an overview of the synthesis of porous metal-organic frameworks (MOFs) materials with MW and US irradiation. MOFs are very interesting materials due to their various potential applications. This review is not meant to serve as a thorough overview of MW- or US-assisted synthesis of MOFs, but is meant to describe the degree of acceleration, phase-selective crystallization, and crystal size reduction in MOF synthesis. Considering these particular aspects of MOF synthesis, the advantages of MW or US irradiation compared with conventional heating have been expounded in detail.