Aanchal Arora

Design and syntheses of novel fluorescent organosilicon-based chemosensors through click silylation: detection of biogenic amines

A concise and useful synthesis of novel 1,2,3-triazole based silatrane (TBS)-scaffolds (2a–e) in good yield from 1,2,3-triazole based triethoxysilane (TBTES)-linkers (1a–e) is described. Click silylation of terminal alkynes with γ-azidopropyltriethoxysilane (AzPTES) was used for the synthesis of TBTES-linkers (1a–e). The synthesized TBS-scaffolds (2a–e) were comprehensively characterized by 1H and 13C NMR, mass spectrometry and single X-ray crystallographic studies. The broad scope of these TBS-scaffolds towards biogenic amines is explored by the use of a CH3CN : H2O (98 : 2; v/v) solvent system. The receptor 2c and 2d shows high affinity towards spermine and histamine, respectively. To the best of our knowledge, the present investigation represents the first report on the use of organosilicon-based chemosensors for the recognition of biogenic amines.

Organosilatranes with thioester-anchored heterocyclic ring assembly: Cu2+ ion binding and fabrication of hybrid silica nanoparticles

This work presents the design, synthesis, UV-Vis absorption properties and Cu2+ ion binding of the organo-silicon complexes (3a–h) with different coordination abilities that are derived from mercaptopropylsilatrane (MPS) and respective heteroaromatic carboxylic acids (1a–h). The prepared thioester based organosilatranes (ThE-OS) have been meticulously characterized by a series of characterization techniques such as elemental analyses, FT-IR, NMR (1H, 13C), LC-MS, and structure of 3e was unambiguously determined by X-ray single crystal analyses. All the compounds have shown judicious absorption enhancement in the intensity as well as λmax values on binding with Cu2+ ions compared to other surveyed metal ions. In addition, it is for the first time that the hybrid silica nanoparticles (H-SiNPs) bearing a thioester linkage in the silica framework are reported. The synthesis was achieved conveniently by an in situ co-condensation reaction of tetraethyl orthosilicate (TEOS) with the corresponding ThE-OS. The derivatization of silica is confirmed by FT-IR, 13C and 29Si solid state CP-MAS NMR, UV-Vis, TEM, XRD, TGA and EDX techniques. Furthermore, the H-SiNPs have exhibited greater affinity towards Cu2+ ions than the parent ThE-OS.

Synthetic approach towards ‘click’ modified chalcone based organotriethoxysilanes; UV-Vis study

The efficient linkage of a conjugate chalcone to n-propyltriethoxysilanes (nPTES) via a 1,2,3-triazole with good yields is reported. The synthesis involves a Claisen–Schmidt condensation reaction followed by a copper(I) catalyzed azide–alkyne cycloaddition (CuAAC) reaction. Two different approaches were followed for the synthesis of organotriethoxysilanes (OTES), however, only one pathway was found to be an efficient synthetic route. The performance of the click reaction under thermal reaction conditions has been optimized using [CuBr(PPh3)3] as catalyst. A photoelectronic spectroscopy study in the UV-Vis region showed significant absorption maxima in the range of 300–325 nm. Moreover, the solvatochromic aspects showing the effect of solvent polarity on the absorption maxima was investigated for the first time on functionalised OTES.

Thioester-appended organosilatranes: synthetic investigations and application in the modification of magnetic silica surfaces

The present investigation discloses a series of new organosilicon derivatives (3a–k) tailored with substituted benzoic acid modules (1a–k) via thioesterification with 3-mercaptopropylsilatrane (MPS). Product formation was authenticated using elemental analyses and different spectroscopic methods comprising FT-IR, NMR [1H, 13C] and LC-MS (Q-TOF). Thereafter, complete structural elucidation of compounds 3c and 3f was achieved by the single crystal X-ray technique. Photo-electronic inspection of all compounds by UV-Vis spectroscopy revealed their sensitivity towards substitution patterns. In addition, this is the first time that the potential of a silatranyl moiety has been tested for the modification of a silica surface pre-decorated with a magnetite core. The synthesis was achieved through a facile methodology involving chemical bonding at each stage, which proceeded without any external surfactant or template. The course of the reaction was followed by FT-IR, UV-Vis, XRD, TEM, FESEM, EDX and TGA techniques. Furthermore, the hybrid nanomaterial possessed significant sensorial ability toward copper ions, which makes the present protocol favourable for the construction of a new class of chelating ligands with an in-built multifunctional nanodevice.

Heteroaryl chalcone allied triazole conjugated organosilatranes: synthesis, spectral analysis, antimicrobial screening, photophysical and theoretical investigations

A series of heteroaryl tethered triazole conjoined organosilatranes were synthesized following an archetypal click reaction. The reaction sequence follows the initial generation of acetylinic Schiff bases (3a–3c, 4a–4c) which undergo 3 + 2 cycloaddition with 3-azidopropyltriethoxysilane (3-AzPTES) to give organotriethoxysilanes (5a–5c, 6a–6c) which were ultimately amended into their five-membered organosilatrane descendants (7a–7c, 8a–8c). The synthesized compounds were fully characterized by IR, 1H, 13C, mass spectrometry techniques and elemental analysis. Also, the complete structure elucidation of 7a and 8a was achieved via X-ray crystallography. The photophysical studies of the entire sequence of organosilatranes were performed in solvents of varying polarity to gain an insight into their solvatochromic behaviour. The results reveal that the molecules display trivial positive solvatochromism suggesting a high dipole moment of the excited state that has also been concurrently supported by the results derived from the Lippert–Mataga equation. Further, the molecular structures and photophysical properties of the organosilatranes were also studied theoretically by applying the IEFPCM model that mimics the desired solvent in combination with the TDDFT approach. Theoretical results were found to be in absolute accord with the experimental values. Additionally, several DFT based reactivity descriptors are reported presenting a meticulous view into the relative stability and reactivity of the chalcone linked organosilatranes. Further, all the organosilatranes were screened for their physiochemical and pharmacokinetic delineation by computational analysis and then investigated for their antimicrobial activities against different strains of bacteria and fungi. Compounds 8b and 8c were found to be the most potent antibacterial and antifungal agents, respectively.