Spectroscopic and Colorimetric Studies for Anions with a New Urea-Based Molecular Cleft

Kundu, Sanchita; Egboluche, Tochukwu Kevin; Yousuf, Zehra; Hossain, Md. Alamgir

doi:10.3390/chemosensors9100287

Cited by 4 publications

(6 citation statements)

References 50 publications

(71 reference statements)

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“…This paper describes a hexafunctional tripodal receptor consisting of a urea-based inner cleft and a thiourea-based outer cleft that provides perfect sites for two anions within a single cavity via strong H-bonding interactions, encapsulating one anion in its thiourea cleft, followed by a second encapsulation in its urea cleft. Kundu, S.; Egboluche, T. K.; Yousuf, Y.; Hossain, M. A. Spectroscopic and Colorimetric Studies for Anions with a New Urea-Based Molecular Cleft. Chemosensors 2021 , 9 , 287 . This paper describes the synthesis and anion binding properties of a urea-based dipodal molecular cleft by spectroscopic and colorimetric techniques that forms a 1:2 complex with an anion, exhibiting strong selectivity for fluoride and displaying visible color change for fluoride, acetate, bicarbonate, and dihydrogen phosphate. …”

Section: Key Referencesmentioning

confidence: 99%

“…Changing the spacer from a m -xylyl to a p -xylyl framework, a urea-based receptor 4 was synthesized and studied for anion binding by 1 H NMR, UV–vis, and colorimetric techniques in DMSO . The receptor exhibited an absorption band at λ max = 354 nm.…”

Section: Bifunctional Dipodal Receptorsmentioning

confidence: 99%

“…Changing the spacer from a m-xylyl to a p-xylyl framework, a urea-based receptor 4 was synthesized and studied for anion binding by 1 H NMR, UV−vis, and colorimetric techniques in DMSO. 4 The receptor exhibited an absorption band at λ max = 354 nm. The incremental addition of fluoride, acetate, bicarbonate, or dihydrogen phosphate to 4 resulted in a gradual red shift in the absorbance band, displaying isosbestic points at 400, 382, 398, and 390 nm, respectively.…”

Section: Rigid Dipodal Receptorsmentioning

confidence: 99%

“…Kundu, S.; Egboluche, T. K.; Yousuf, Y.; Hossain, M. A. Spectroscopic and Colorimetric Studies for Anions with a New Urea-Based Molecular Cleft. Chemosensors 2021 , 9 , 287 . This paper describes the synthesis and anion binding properties of a urea-based dipodal molecular cleft by spectroscopic and colorimetric techniques that forms a 1:2 complex with an anion, exhibiting strong selectivity for fluoride and displaying visible color change for fluoride, acetate, bicarbonate, and dihydrogen phosphate.…”

Section: Key Referencesmentioning

confidence: 99%

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Urea- and Thiourea-Based Receptors for Anion Binding

2023

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Conspectus Over the past five decades, significant progress has been made in the field of anion recognition with a diverse variety of synthetic receptors because of the fundamental importance of anions in chemical, environmental, and biological processes. In particular, urea- and thiourea-based molecules offering directional binding sites are attractive receptors for anions due to their ability to bind anions employing primarily hydrogen-bonding interactions under neutral conditions and have gained a recent paramount attention in the area of supramolecular chemistry. The presence of two imine (−NH) groups on each urea/thiourea functionality in these receptors gives them potential for excellent binding of an anion, mimicking the natural binding process in living cells. The increased acidity offered by thiocarbonyl groups (CS) in a thiourea-functionalized receptor could enhance its anion binding ability as compared to its analogous urea-based receptor containing a carbonyl (CO) group. During the last several years, our group has been involved in exploring a wide variety of synthetic receptors, and we have studied them with anions experimentally and computationally. In this Account, we will highlight the overall summary of our group’s efforts focusing on anion coordination chemistry of urea- and thiourea-based receptors with varying linkers (rigid and flexible), dimensions (dipodal and tripodal), and functionalities (bifunctional, trifunctional, and hexafunctional). Depending on the linkers and attached groups, bifunctional-based dipodal receptors can bind anions forming 1:1 or 1:2 complexes. A dipodal receptor with flexible aliphatic or rigid m-xylyl linkers forms a cleft to bind a single anionic species in the pocket. However, a dipodal receptor with p-xylyl linkers binds anions in both 1:1 and 1:2 binding modes. As compared to a dipodal receptor, a tripodal receptor provides a more organized cavity for an anion, forming predominantly a 1:1 complex, while the binding strength and selectivity are influenced by linking chains and terminal groups. A hexafunctional-based tripodal receptor bridged with o-phenylene groups provides two clefts that can host two small anions or one large anion. However, a hexafunctional receptor with p-phenylene groups as linkers binds two anions, one at an inner pocket and the other at an outer pocket. It was shown that the presence of suitable chromophores at the terminal groups makes the receptor useful for the naked-eye detection for certain anions (e.g., fluoride, acetate) in solution. The field of anion binding chemistry is rapidly growing, and this Account aims to provide fundamental aspects influencing the binding strength and selectivity of anionic species with abiotic receptors which might eventually be useful for the development of new devices for binding, sensing, and separating biologically and environmentally important anions.

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Section: Key Referencesmentioning

confidence: 99%

Section: Bifunctional Dipodal Receptorsmentioning

confidence: 99%

Section: Rigid Dipodal Receptorsmentioning

confidence: 99%

Section: Key Referencesmentioning

confidence: 99%

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Urea- and Thiourea-Based Receptors for Anion Binding

2023

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“…Anions play an important role in daily life, especially in biology, medicine, catalysis, industry and agriculture [1]. In reality, anions can have adverse effects on aquatic environment and human health when present beyond the normally acceptable range [2].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Spectroscopic Evaluations and UV-Vis Titration Studies of New Symmetrical Amide Compounds Derived from N-6-[(4-pyridylmethylamino)carbonyl]-pyridine-2-carboxylic Acid Methyl Ester

Abdul Kadir,

Haris,

Mohamed Zuki

et al. 2024

Trends Sci

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In this study, 2 flexible and pre-organized tetraamide compounds derived from N-6-[(4-pyridylmethylamino)carbonyl]-pyridine-2-carboxylic acid methyl ester namely 1,2-bis[N,N’-6-(4-pyridylmethylamido)pyridyl-2-carboxyamido]pentane (L1) and 1,2-bis[N,N’-6-(4-pyridylmethylamido)pyridyl-2-carboxyamido]hexane (L2) have been successfully synthesized when reacted with diamines in 1:2 ratio. These new compounds were built from combination of 3 main components, as a trend requires for anion receptor which are (i) 2,6-pyridine dicarboxamide moieties as targeted anion binding host, (ii) amino methyl pyridine pendants arms as the flexible moieties and (iii) pentyl (-C5H10-) and hexyl (-C6H12-) unit as the spacer. Compounds L1-L2 were fully characterized by using elemental analyzer, Fourier transform infrared (FTIR) spectroscopy, gas chromatography-mass spectroscopy (GC-MS), 1H, 2D NOESY and 13C Nuclear Magnetic Resonance (NMR) spectroscopies, and Ultraviolet-visible (UV-Vis) spectroscopies. In this study, anion titration methods were used to identify the affinity towards selected anions. The results showed that L1 (having a pentyl spacer) had the highest affinity towards phosphate anions as compared to L2, where the red shift changes were observed in the UV-vis spectrum at the amide region. HIGHLIGHTS Two novel amide compounds with flexible and pre-organized structure are designed for use as potential anion receptors The flexible moieties at the amide and the linker allow hydrogen bonding interaction of the molecules with variety anions with different geometries Anion titration studies revealed good affinities towards phosphate anions as suggested in Hofmeister trend GRAPHICAL ABSTRACT

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