Arwa Makki - Academia.edu (original) (raw)

Papers by Arwa Makki

In present research, we synthesized cobalt-based silica nanocomposites (Co-SiO 2) from cobalt nit... more In present research, we synthesized cobalt-based silica nanocomposites (Co-SiO 2) from cobalt nitrate [Co(NO 3) 2 ] and tetraethoxysilane (TEOS) precursors by using a simple sol-gel method followed by supercritical drying techniques. The physicochemical and textual properties of the as synthesized nano composites were thoroughly investigated. The results indicated that the Co-SiO 2 aerogels demonstrated homogeneous dispersion cobalt nanoparticles within silica matrix with mesoporous morphology, large specific surface area (802 m 2 /g) and larger pore size (9 nm) with less volume shrinkage. The physicochemical properties of the cobalt based silica nanomaterial were characterized by XRD, SEM, N 2 adsorptiondesorption and FTIR techniques. Cobalt-based silica nanocomposites can be produced using TEOS-based precursor and supercritical drying techniques. The prepared (Co-SiO 2) nanocatalyst due to its magnetic nature with higher surface area (802 m 2 /g) can be utilized in many emerging fields such as catalysis, water desalination, water splitting, gas-sensing application and organic pollutant degradation.

Studies and development of artificial metalloenzymes have developed into vibrant areas of researc... more Studies and development of artificial metalloenzymes have developed into vibrant areas of research. It is expected that artificial metalloenzymes will be able to combine the best of enzymatic and homogenous catalysis, that is, a broad catalytic scope, high selectivity and activity under mild, aqueous conditions. Artificial metalloenzyme consist of a host protein and a newly introduced artificial metal center. The host protein merely functions as ligand controlling selectivity and augmenting reactivity, while the metal center determines the reactivity. Potential applications range from catalytic production of fine chemicals and feedstock to electron transfer utilization (e.g. fuel cells, water splitting) and medical research (e.g. metabolic screening). Particularly modern asymmetric synthesis is expected to benefit from a successful combination of the power of biocatalysis (substrate conversion via multi-step or cascade reactions, potentially immortal catalyst, unparalleled selectivity and optimization by evolutionary methods) with the versatility and mechanism based optimization methods of homogeneous catalysis. However, so far systems are either limited in structural diversity (biotin-avidin technology) or fail to deliver the selectivities expected (covalent approaches). This thesis explores a novel strategy based on the site-selective incorporation of unnatural, metal binding amino acids into a host protein. The unnatural amino acids can either serve directly as metal binding centers can be used as anchoring points for artificial metallo-cofactors. The identification expression, purification and modification of a suitable protein scaffolds

Green Chemistry, 2018

A transition metal free, reagent free, only water based, greener protocol for the allylic alkylat... more A transition metal free, reagent free, only water based, greener protocol for the allylic alkylation, allylic amination, and O-allylation of (E)-1,3-diphenylallyl acetate is described.

The Journal of organic chemistry, Feb 16, 2018

A mild aqueous protocol for palladium catalyzed Miyaura borylation of aryl iodides, aryl bromides... more A mild aqueous protocol for palladium catalyzed Miyaura borylation of aryl iodides, aryl bromides and aryl chlorides with tetrahydroxydiboron (BBA) as a borylating agent is developed. The developed methodology requires low catalyst loading of Bedford-type palladacycle catalyst (0.05 mol %) and works best under mild reaction conditions at 40 °C in short time of 6 h in water. In addition, our studies show that for Miyaura borylation using BBA in aqueous condition, maintaining a neutral reaction pH is very important for reproducibility and higher yields of corresponding borylated products. Moreover, our protocol is applicable for a broad range of aryl halides, corresponding borylated products are obtained in excellent yields up to 93% with 29 examples demonstrating its broad utility and functional group tolerance.

ACS Catalysis, 2019

Artificial metalloenzymes (ArMs) have high potential in biotechnological applications as they com... more Artificial metalloenzymes (ArMs) have high potential in biotechnological applications as they combine the versatility of transition-metal catalysis with the substrate selectivity of enzymes. An ideal host protein should allow high-yield recombinant expression, display thermal and solvent stability to withstand harsh reaction conditions, lack nonspecific metal-binding residues, and contain a suitable cavity to accommodate the artificial metal site. Moreover, to allow its rational functionalization, the host should provide an intrinsic reporter for metal binding and structural changes, which should be readily amendable to high-resolution structural characterization. Herein, we present the design, characterization, and de novo functionalization of a fluorescent ArM scaffold, named mTFP*, that achieves these characteristics. Fluorescence measurements allowed direct assessment of the scaffold's structural integrity. Protein X-ray structures and transition metal Forster resonance energy transfer (tmFRET) studies validated the engineered metal coordination sites and provided insights into metal binding dynamics at the atomic level. The implemented active metal centers resulted in ArMs with efficient Diels−Alderase and Friedel−Crafts alkylase activities.

In present research, we synthesized cobalt-based silica nanocomposites (Co-SiO 2) from cobalt nit... more In present research, we synthesized cobalt-based silica nanocomposites (Co-SiO 2) from cobalt nitrate [Co(NO 3) 2 ] and tetraethoxysilane (TEOS) precursors by using a simple sol-gel method followed by supercritical drying techniques. The physicochemical and textual properties of the as synthesized nano composites were thoroughly investigated. The results indicated that the Co-SiO 2 aerogels demonstrated homogeneous dispersion cobalt nanoparticles within silica matrix with mesoporous morphology, large specific surface area (802 m 2 /g) and larger pore size (9 nm) with less volume shrinkage. The physicochemical properties of the cobalt based silica nanomaterial were characterized by XRD, SEM, N 2 adsorptiondesorption and FTIR techniques. Cobalt-based silica nanocomposites can be produced using TEOS-based precursor and supercritical drying techniques. The prepared (Co-SiO 2) nanocatalyst due to its magnetic nature with higher surface area (802 m 2 /g) can be utilized in many emerging fields such as catalysis, water desalination, water splitting, gas-sensing application and organic pollutant degradation.

Studies and development of artificial metalloenzymes have developed into vibrant areas of researc... more Studies and development of artificial metalloenzymes have developed into vibrant areas of research. It is expected that artificial metalloenzymes will be able to combine the best of enzymatic and homogenous catalysis, that is, a broad catalytic scope, high selectivity and activity under mild, aqueous conditions. Artificial metalloenzyme consist of a host protein and a newly introduced artificial metal center. The host protein merely functions as ligand controlling selectivity and augmenting reactivity, while the metal center determines the reactivity. Potential applications range from catalytic production of fine chemicals and feedstock to electron transfer utilization (e.g. fuel cells, water splitting) and medical research (e.g. metabolic screening). Particularly modern asymmetric synthesis is expected to benefit from a successful combination of the power of biocatalysis (substrate conversion via multi-step or cascade reactions, potentially immortal catalyst, unparalleled selectivity and optimization by evolutionary methods) with the versatility and mechanism based optimization methods of homogeneous catalysis. However, so far systems are either limited in structural diversity (biotin-avidin technology) or fail to deliver the selectivities expected (covalent approaches). This thesis explores a novel strategy based on the site-selective incorporation of unnatural, metal binding amino acids into a host protein. The unnatural amino acids can either serve directly as metal binding centers can be used as anchoring points for artificial metallo-cofactors. The identification expression, purification and modification of a suitable protein scaffolds

Green Chemistry, 2018

A transition metal free, reagent free, only water based, greener protocol for the allylic alkylat... more A transition metal free, reagent free, only water based, greener protocol for the allylic alkylation, allylic amination, and O-allylation of (E)-1,3-diphenylallyl acetate is described.

The Journal of organic chemistry, Feb 16, 2018

A mild aqueous protocol for palladium catalyzed Miyaura borylation of aryl iodides, aryl bromides... more A mild aqueous protocol for palladium catalyzed Miyaura borylation of aryl iodides, aryl bromides and aryl chlorides with tetrahydroxydiboron (BBA) as a borylating agent is developed. The developed methodology requires low catalyst loading of Bedford-type palladacycle catalyst (0.05 mol %) and works best under mild reaction conditions at 40 °C in short time of 6 h in water. In addition, our studies show that for Miyaura borylation using BBA in aqueous condition, maintaining a neutral reaction pH is very important for reproducibility and higher yields of corresponding borylated products. Moreover, our protocol is applicable for a broad range of aryl halides, corresponding borylated products are obtained in excellent yields up to 93% with 29 examples demonstrating its broad utility and functional group tolerance.

ACS Catalysis, 2019

Artificial metalloenzymes (ArMs) have high potential in biotechnological applications as they com... more Artificial metalloenzymes (ArMs) have high potential in biotechnological applications as they combine the versatility of transition-metal catalysis with the substrate selectivity of enzymes. An ideal host protein should allow high-yield recombinant expression, display thermal and solvent stability to withstand harsh reaction conditions, lack nonspecific metal-binding residues, and contain a suitable cavity to accommodate the artificial metal site. Moreover, to allow its rational functionalization, the host should provide an intrinsic reporter for metal binding and structural changes, which should be readily amendable to high-resolution structural characterization. Herein, we present the design, characterization, and de novo functionalization of a fluorescent ArM scaffold, named mTFP*, that achieves these characteristics. Fluorescence measurements allowed direct assessment of the scaffold's structural integrity. Protein X-ray structures and transition metal Forster resonance energy transfer (tmFRET) studies validated the engineered metal coordination sites and provided insights into metal binding dynamics at the atomic level. The implemented active metal centers resulted in ArMs with efficient Diels−Alderase and Friedel−Crafts alkylase activities.