Khaleel I. Assaf

Khaleel I. Assaf
Al-Balqa Applied University

Dr

About

152
Publications
29,877
Reads
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4,895
Citations
Additional affiliations
September 2018 - October 2020
Constructor University Bremen gGmbH
Position
  • Researcher
February 2015 - August 2018
Constructor University Bremen gGmbH
Position
  • PostDoc Position
October 2010 - February 2015
Constructor University Bremen gGmbH
Position
  • PhD Student
Education
October 2010 - February 2015
August 2006 - May 2009
Hashemite University
Field of study
  • Chemistry
August 2003 - August 2006
Hashemite University
Field of study
  • Chemistry

Publications

Publications (152)
Article
Full-text available
The synthesis and characterization of nine palladium(II) complexes featuring β‐ketoiminato ligands of type [Pd(ArNacac)2] (4) with Ar=2‐chlorolphenyl (a); 3‐chlorophenyl (b); 4‐chlorophenyl (c); 2,3‐dichlorophenyl (d); 2,4‐dichlorophenyl (e); 2,6‐dichlorophenyl (f); 3,5‐dichlorophenyl (g); 2,4,5‐trichlorophenyl (h); 2,4,6‐trichlorophenyl (i) is rep...
Article
Full-text available
The molecular confinement within rigid macrocyclic receptors can trigger catalytic activity and steer the selectivity of organic reactions. In this work, the dimerization of methylcyclopentadiene (MCPD) isomers in the presence of cucurbit[7]uril (CB7) was found to display, besides a large rate acceleration, a striking regioselectivity in aqueous so...
Article
Full-text available
Monitoring medications in biological fluids is an essential aspect of patient care, particularly in cases of altered mental status where accurate diagnosis, effective treatment, and even forensic examinations are crucial. In this study, a new approach combining hydrophobic-deep-eutectic and solvent-bar-micro-extraction (HDE-SBME) followed by a high...
Article
Full-text available
Cucurbiturils (CBn) are known to establish stable host–guest complexes with a variety of drug molecules. Herein, the supramolecular complexation between cucurbit[7]uril (CB7) and phenylephrine hydrochloride is reported in aqueous solution. Phenylephrine forms inclusion complex with CB7 with high binding affinity (Kaffinity = 4.0 × 10⁶ M⁻¹), which a...
Article
Engineered molecules with tailored molecular structures have the potential to advance various disciplines by enhancing the properties of biological membranes. In this study, we investigated the fundamental interfacial behavior of...
Article
Porous organic polymers (POPs) and covalent organic frameworks (COFs) are hierarchical nanomaterials with variable applications. To our knowledge, a first time reported post-modified, non-renewable, DMSO-soluble M-POP/1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) upon atmospheric H2O/CO2...
Preprint
Full-text available
The dodecaborate anion (B 12 H 12 2– , DDB) has been qualitatively considered as a strong electron donor. Here, we report the Hammett substituent constant for DDB and its amino derivative (DDB–NH), which are among the strongest electron donors reported so far, on a scale that employs the ¹⁹ F chemical shift of meta- and para-substituted fluorobenze...
Article
Full-text available
Keywords: Hydrophobic deep eutectic solvent Solvent bar microextraction Parabens Response surface methodology and central composite design HPLC-DAD Urine and plasma a b s t r a c t Parabens are antimicrobial preservatives with extensive applications in cosmetics, toiletries, pharmaceuticals , and food. Considering the legitimate concerns relating t...
Article
A multi-active site 1,1',1''-(2-hydroxybenzene-1,3,5-triyl)tris(N-benzyl-N,N-dimethylmethanammonium)bromide ( 3 ) and hierarchical ionic polymers 9 , 11 , 13 , and 16 have been synthesized. Compound 3 showed the best catalytic activity under co-catalyst free and mild reaction...
Article
A one-pot solvothermal, polyurea (PU) synthesis was reported using propylene carbonate (PC) and methylene-4,4’-dianiline (MDA), organocatalyzed by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in toluene. The applied method was performed under auxiliary-free (halogen-, metal-,...
Article
Full-text available
Conspectus The past decade has seen significant progress in the understanding and appreciation of the importance of London dispersion interactions (LDIs) in supramolecular systems and solutions. The Slater–Kirkwood formula relates LDIs to the molecular polarizabilities of the two interacting molecular species (α) and their interaction distance (a...
Article
Full-text available
Hybrid organic‐inorganic molecules have recently received great interest due to their unique properties, which give access to their implementation in biological and material sciences. Herein, a new synthetic approach for the direct‐linkage of the purely inorganic dodecaborate cluster to organic building blocks through B−C bond is established, using...
Article
Nowadays, functionalized cucurbit[ n ]urils are considered one of the most important examples of macromolecules and have attracted a lot of attention due to their potential applications in several sectors. In the present work monomethyl‐cucurbit[7]uril ( 3 ) was synthesized for the first time through facile synthetic route with high purity form by...
Article
Full-text available
Large water-soluble anions with chaotropic character display surprisingly strong supramolecular interactions in water, for example, with macrocyclic receptors, polymers, biomembranes, and other hydrophobic cavities and interfaces. The high affinity is traced back to a hitherto underestimated driving force, the chaotropic effect, which is orthogonal...
Article
The design of green catalysts for CO2 utilization purposes is considered a great challenge and a motivation for a sustainable future. In this work, a first-time zinc adeninium bromide (Zn-AHBr) was synthesized and fully characterized using far and mid ATR-FTIR, 1D and 2D NMR spectroscopy, including 1H, 13C and [1H,15N] correlation spectroscopy (HMB...
Article
In this work, molecular dynamics (MD) simulations and time-dependent density functional theory (TD-DFT) calculations were applied to study the formation of binary and ternary complexes between cucurbit[8]uril (CB8) and three tryptophan-containing tripeptides (WGG, GWG, and GGW), as well as heteroternary complexes of the tripeptides in the presence...
Article
Recently, we have investigated the cucurbit[7]uril (CB7) recognition of the α- and β-anomers of neutral, protonated, and acetylated forms of glucosamine in water. In the present work, we employed molecular dynamics (MD) and thermodynamic integration methods (TI) to investigate the recognition of these molecules by cucurbit[6]uril (CB6) and cucurbit...
Article
Herein, a first-time, one pot synthesis of 1,3-bis(3-(1,3-dioxoisoindolin-2-yl)propyl)-1H-imidazol-3-ium bromide (7), which can be considered a vital precursor for the facile synthesis of highly pure task specific ionic liquids (TSILs), and other derivatives including unprecedented protic and aprotic systems is reported. Catalyst decoration includi...
Article
Perhalogenated boron clusters derived from B12Br122-, a superchaotropic dianion with a globular icosahedral shape, serve as inorganic cavity binders for cyclodextrins (CDs), in particular for large CDs (γ-CD and δ-CD), with high binding affinity (Ka > 106 M-1) in aqueous solution. This opens the door for applications of this anchoring moiety by lin...
Article
Full-text available
In the present work, we used molecular dynamics (MD) and TD‐DFT calculations to investigate the formation of the heteroternary complexes formed by cucurbit[8]uril (CB8) with amino acids (AAs), tryptophan, phenylalanine and tyrosine in the presence of different auxiliary ligands (ALs): methyl viologen (MV), 2,7‐dimethyldiazaphenanthrenium (DPT) and...
Article
Full-text available
The supramolecular complexation of doxepin (DOX) with cucurbit[7]uril (CB7) was investigated in aqueous solution. The results indicated the formation of a host-guest complex, as verified by complexation-induced chemical shifts in the NMR experiments and supported by quantum-chemical calculations, in which the alkylammonium tail of DOX was found to...
Article
We report the synthesis and monolayer properties of conventional and gemini surfactants composed of nicotinic acid-based head groups with an emphasis on assessing how chemical structures affect the behavior of monolayers. A combination of Brewster angle microscopy and atomic force microscopy showed that pure hexadecyl nicotinate formed rippled stra...
Article
Full-text available
We report on the reaction of ethylene-terminated heteroatoms (C2X; X = N, O, and S) with CS2/CO2 using Mukaiyama reagent (2-chloro-1-methylpyridinium iodide, CMPI) as a promoter for the preparation of imidazolidin-2-one, oxazolidin-2-one, 1,3-dioxolan-2-one, 1,3-dithiolan-2-one, and their thione counterparts at ambient temperature and pressure. Spe...
Article
Thermolysis of a urethane end group was observed as a first time phenomenon during activation. This unzipping mechanism revealed a new amine tethering point producing a diamine-terminated oligourea ([10]-OU), acting as a green sorbent for CO2 capturing. The oligomer backbites its end group to form propylene carbonate (PC), as proved by in situ TGA-...
Article
We investigate host-guest complexation between cucurbit[7]uril and the α- and β-anomers of glucosamine, in its neutral (GN), protonated (GP), and acetylated (GA) forms. Molecular dynamics simulations (MD) were used to study the structures of the resulting inclusion complexes and their dynamics. The binding affinities of the complexes were determine...
Article
Full-text available
The membrane translocation of hydrophilic substances constitutes a challenge for their application as therapeutic compounds and labelling probes1–4. To remedy this, charged amphiphilic molecules have been classically used as carriers3,5. However, such amphiphilic carriers may cause aggregation and non-specific membrane lysis6,7. Here we show that g...
Article
Full-text available
Selective binding of amino acids, peptides, and proteins by synthetic molecules and elucidation of the geometry and dynamics of the resulting complexes and their strengths are active areas of contemporary research. In recent work, we analyzed via molecular dynamics (MD) simulations the complexes formed between cucurbit[7]uril (CB7) and three aromat...
Article
Full-text available
This study aimed to clarify the physico-chemical properties of cucurbit[7]uril (CB[7]) and cinnamaldehyde (Cinn) inclusion complexes (CB[7]-Cinn) and their resulting antitumor activity. CB[7]-Cinn inclusion complexes were prepared by a simple experimental approach and fully characterized for their stoichiometry, formation constant, particle size an...
Article
Full-text available
Molecular dynamics simulations were performed in aqueous solution to elucidate an atomistic level picture of complex formation between cucurbit[7]uril (CB7) and three standard aromatic amino acids: tyrosine, tryptophan, and phenylalanine. It was found that all three amino acids formed stable host–guest complexes with CB7, in which the side chain wa...
Article
Full-text available
A new set of hybrid guest molecules bearing organic and inorganic residues have been studied for their recognition by cyclodextrins in aqueous solution. The guest molecules consist of nitroanilines linked through their amino group to the dodecahydrido-closo-dodecaborate cluster B12H122-, which serves as an anchor group. They show sizable affinity t...
Article
Full-text available
In this study, the formation of a host-guest inclusion complex between cucurbit[7]uril (CB[7]) and thymoquinone (TQ) was investigated in aqueous solution. The formation of a stable inclusion complex, CB[7]-TQ, was confirmed by using different techniques, such as 1H NMR and UV-visible spectroscopy. The aqueous solubility of TQ was clearly enhanced u...
Article
Full-text available
A new fluorescent dye (4PBZC) comprising coumarin (C), piperazine (P), and benzimidazole (BZ) was designed, prepared, and complexed to cucurbit[7]uril (CB7) to detect carnosol (CAR), an anti-breast cancer drug, in sub-nanomolar concentrations utilizing the supramolecular indicator displacement assay strategy, the CB7-assisted pKa shift, and the CB7...
Article
Full-text available
CO2is the most influential greenhouse gas with drastic effects all over the world. Meanwhile, global warming is considered a hot topic to different groups of scientists dealing with the global warming phenomenon. As an alternative to the typically-used scrubbing agent that is heavily used in post-combustion capture technology, namely, monoethanolam...
Preprint
Full-text available
In contrast to Diels-Alder reactions involving heteroatom-containing substrates, the endo dimerization of cyclopentadiene responds only very weakly to changes in microenvironment or the presence of potential catalysts (less than factor of 10 variation), although this pure hydrocarbon reaction has been used as an early model to predict the maximum p...
Preprint
Full-text available
In contrast to Diels-Alder reactions involving heteroatom-containing substrates, the endo dimerization of cyclopentadiene responds only very weakly to changes in microenvironment or the presence of potential catalysts (less than factor of 10 variation), although this pure hydrocarbon reaction has been used as an early model to predict the maximum p...
Article
Adsorption of CO2 on biopolymers such as cellulose (CELL) and chitosan (CS) attracts researchers’ interest, in particular, the aerogel formation with high surface area and unique physical properties. In this work, we investigate the molecular adsorption of CO2 molecule on the CELL and CS surfaces by the density functional theory (DFT), using dimeri...
Article
Although alkanolamines have been systematically utilized for CO2 capture, intensive research efforts are still required to ultimately design more efficient CO2 sorbents with appropriate sorption characteristics. In this article, we have explored a series of diamine-tetraamido macrocyclic molecules with different organic linkers, namely, pyridine, p...
Article
Full-text available
A simple one-pot synthesis process for functionalized mesostructured silica nanoparticles (MSNP) is reported. The novel process demonstrated the possibility to achieve MSNP with a surface area up to 501 m2.g−1 using a phosphonate based nonsilane precursor such as N, N´-bis[4,6-bis(diethylphosphono)-1,3,5-triazin-yl]-1,2-diaminoethane (ED). MSNP obt...
Article
Herein, we explore the use of β -diketones for CO 2 fixation and utilization based on their dual Brønested acid/Lewis base character upon activation by 1,8-diazabicyclo[5.4.0]undec-7-ene ( DBU ) and zinc bromide ( ZnBr 2 ), respectively....
Article
We reported on sustainable, one-pot synthesized caffeine-based compounds as effective, bifunctional, heterogenous, hydrogen-bond-donor organocatalysts for the cycloaddition of CO 2 with several epoxides, supported by a mechanistic study and verified by density functional theory calculations. Two reaction intermediates were isolated during the catal...
Article
Full-text available
A series of water soluble, surface‐active ionic liquids (SAILs), namely, 1‐alkyl‐3‐methyl imidazolium chlorides ([Cn‐mim]Cl) and their mixtures with palmitic acid (PA) are investigated in Langmuir monolayers and Langmuir–Blodgett films. It is inferred from the surface pressure‐area isotherms that C16‐mim‐IL mixes non‐ideally with PA and stabilizes...
Article
The effect of β-cyclodextrin (β-CD) on the spectroscopic properties of mebendazole, MBZ, in aqueous solution was investigated at pH values of 2.0, 4.0, 6.0, 8.0, 10.0, and 12.0, where mebendazole exists as protonated (HMBZ+), neutral (MBZ), or deprotonated (MBZ−) forms. Mebendazole shows two absorption bands at 236 nm and 288 nm at pH 2.0, which ar...
Article
Full-text available
A new classification of green CO2 sorbents, in accordance with green chemistry principles must be developed in order to have low‐carbon footprint scrubbing agents in the near future. In article number 1900121, Abdussalam K. Qaroush and co‐workers review the use of biomaterials such as chitin, cyclodextrin (CD) (ie, CD‐metal–organic frameworks), and...
Article
Full-text available
A fluorescent perylene‐based dye (PDI) was designed with two aromatic moieties at the imide position of the perylene core. The dye displayed contrasting behavior with water‐soluble macrocycles. Cucurbit[n]urils (CB7 and CB8) reduced the self‐aggregation of the dye molecules, while sulfonatocalixarenes (SCX4 and SCX5) and sulfonato‐β‐cyclodextrin (S...
Article
An in situ generated zinc ascorbate pre-catalyst for cyclic carbonates (CCs) synthesis via CO2 coupling with epoxides under ambient conditions was reported. Spectroscopic measurements indicated that CO2 was inserted within the zinc ascorbate complex through the formation of an activated zinc carbonate catalyst upon abstracting the enediol protons w...
Article
(Thio)Urea scaffolds are best known for their importance as intermediates in organic synthesis. In this work, a mechanistic study of the reaction between urea (U), (2-hydroxyethyl)urea (U-EtOH) and thiourea (tU)/NaH in DMSO with CO2 were investigated. While both U/tU reacted with CO2via a 1:2 mechanism through the formation of the keto (thio)carbam...
Article
Full-text available
The supramolecular recognition of closo,closo‐[B21H18]⁻ by cyclodextrins (CDs) has been studied in aqueous solution by isothermal titration calorimetry and nuclear magnetic resonance spectroscopy. These solution studies follow up on previous mass‐spectrometric measurements and computations, which indicated the formation and stability of CD ⋅ B21H18...
Article
Full-text available
Significant progress has been made in the past decades in the capture, storage, and utilization of greenhouse gases, particularly CO2. In general, the synthesis of most of the available CO2 sorbents is not ecofriendly and can require multistep synthesis in order to prepare and/or activate, which is considered a strict violation of green chemistry p...
Article
Cucurbit[n]urils (CBn, n = 6–8) serve as molecular receptors for imidazolium-based ionic liquids (ILs) in aqueous solution. The amphiphilic nature of 1-alkyl-3-methylimidazolium guests (Cnmim), with a cationic imidazolium residue and a hydrophobic alkyl chain, enabled their complexation with CBn through a combination of the hydrophobic effect and i...
Article
A comparative model for the chemisorption of CO2 is explored via three representative reaction pathways: carboxylation of cyclohexanone, carbonation of cyclohexanol, and carbamation of cyclohexylamine. The model substrates were activated by using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, an amidine superbase). For each of these reactions, the format...