MOF-based nanocomposites as transduction matrices for optical and electrochemical sensing

Metal Organic Frameworks (MOFs), a class of crystalline microporous materials have been into research limelight lately due to their commendable physio-chemical properties and easy fabrication methods. They have enormous surface area which can be a working ground for innumerable molecule adhesions and site for potential sensor matrices. Their biocompatibility makes them valuable for in vitro detection systems but a compromised conductivity requires a lot of surface engineering of these molecules for their usage in electrochemical biosensors. However, they are not just restricted to a single type of transduction system rather can also be modified to achieve feat as optical (colorimetry, luminescence) and electro-luminescent biosensors. This review emphasizes on recent advancements in the area of MOF-based biosensors with focus on various MOF synthesis methods and their general properties along with selective attention to electrochemical, optical and opto-electrochemical hybrid biosensors. It also summarizes MOF-based biosensors for monitoring free radicals, metal ions, small molecules, macromolecules and cells in a wide range of real matrices. Extensive tables have been included for understanding recent trends in the field of MOF-composite probe fabrication. The article sums up the future scope of these materials in the field of biosensors and enlightens the reader with recent trends for future research scope.

Hierarchical Mesoporous SSZ-13 Chabazite Zeolites for Carbon Dioxide Capture

Artificial carbon dioxide capture is an alternative method to remove the carbon dioxide already accumulated in the atmosphere as well as to stop its release at its large-scale emission points at the source, such as at power plants. However, new adsorbents are needed to make the approach feasible. For this purpose, in this study, hierarchical mesoporous-microporous chabazite-type zeolites were synthesised by applying a dual-templating method. The microporous zeolite structure-directing agent N,N,N-trimethyl-1-adamantanammonium hydroxide was combined with an organosilane mesopore-generating template, 3-(trimethoxysilyl)propyl octadecyl dimethyl ammonium chloride. Materials were characterised for their structural and textural properties and tested for their carbon dioxide capture capacity both in their original sodium form and in their proton-exchanged form by means of breakthrough curve analysis and sorption isotherms. The influence of template ratios on their structure, carbon dioxide capture, and capacity have been identified. All mesoporous materials showed fast adsorption-desorption kinetics due to a reduction in the steric limitations via the introduction of a meso range network of pores. The hierarchical zeolites are recyclable with a negligible loss in crystallinity and carbon dioxide capture capacity, which makes them potential materials for larger-scale application.

Nanoscale Metal-Organic Frameworks: Recent developments in synthesis, modifications and bioimaging applications

Porous Metal-Organic Frameworks (MOFs) have emerged as eye-catching materials in recent years. They are widely used in numerous fields of chemistry thanks to their desirable properties. MOFs have a key role in the development of bioimaging platforms that are hopefully expected to effectually pave the way for accurate and selective detection and diagnosis of abnormalities. Recently, many types of MOFs have been employed for detection of RNA, DNA, enzyme activity and small-biomolecules, as well as for magnetic resonance imaging (MRI) and computed tomography (CT), which are valuable methods for clinical analysis. The optimal performance of the MOF in the bio-imaging field depends on the core structure, synthesis method and modifications processes. In this review, we have attempted to present crucial parameters for designing and achieving an efficient MOF as bioimaging platforms, and provide a roadmap for researchers in this field. Moreover, the influence of modifications/fractionalizations on MOFs performance has been thoroughly discussed and challenging problems have been extensively addressed. Consideration is mainly focused on the principal concepts and applications that have been achieved to modify and synthesize advanced MOFs for future applications.

Heterogeneous Catalysts for the Conversion of Glucose into 5-Hydroxymethyl Furfural

Lignocellulosic biomass, a cheap and plentiful resource, could play a key role in the production of sustainable chemicals. The simple sugars contained in the renewable lignocellulosic biomass can be converted into commercially valuable products such as 5-hydroxymethyl furfural (HMF). A platform molecule, HMF can be transformed into numerous chemical products with potential applications in a wide variety of industries. Of the hexoses contained in the lignocellulosic biomass, the successful production of HMF from glucose has been a challenge. Various heterogeneous catalysts have been proposed over the last decade, ranging from zeolites to metal organic frameworks. The reaction conditions vary in the reports in the literature, which makes it difficult to compare catalysts reported in different studies. In addition, the slight variations in the synthesis of the same material in different laboratories may affect the activity results, because the selectivity towards desired products in this transformation strongly depends on the nature of the active sites. This poses another difficulty for the comparison of different reports. Furthermore, over the last decade the new catalytic systems proposed have increased profoundly. In this article, we summarize the heterogeneous catalysts: Metal Organic Frameworks (MOFs), zeolites and conventional supported catalysts, that have been reported in the recent literature and provide an overview of the observed catalytic activity, in order to provide a comparison.

Cauliflower-like hierarchical silicalite-1 supported AuNPs toward improved catalytic reduction of p-nitrophenol

AuNP impregnated cauliflower-like hierarchical silicalite-1 particles were synthesized via a steam-assisted crystallization (SAC) method followed by impregnation of AuNPs. The product showed improved catalytic reduction of 4-NP to 4-AP with an apparent rate constant (k) and activity parameter (κ) of 7.7 × 10⁻³ s⁻¹ and 146.4 s⁻¹ g⁻¹, respectively.

Cooperative structure direction of organosilanes and tetrapropylammonium hydroxide to generate hierarchical ZSM-5 zeolite with controlled porous structure

Hierarchical ZSM-5 zeolites of controlled porous structure were realized by the cooperative direction of organosilanes and tetrapropylammonium hydroxide.

Highly mesoporous SAPO-11 molecular sieves with tunable acidity: facile synthesis, formation mechanism and catalytic performance in hydroisomerization of n-dodecane

Hierarchical SAPO-11 molecular sieves with tunable acidity fabricated by a facile dry-gel conversion approach show excellent performance in hydroisomerization of n-dodecane.