Exploring the gem-dimethyl effect in the formation of imine-based macrocycles and cages

Madhu, Suresh; Rashmi, E. V.; Gonnade, Rajesh G.; Sanjayan, Gangadhar J.

doi:10.1039/c7nj02069d

Cited by 6 publications

(5 citation statements)

References 31 publications

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“…The imine-based macrocycle (M1) was synthesized using a modified reported procedure. [16] The obtained macrocycle was characterized by 1 H, 13 C NMR and IR spectroscopy where experimental data matched well with the reported results (Figures S3-S5). For post-synthesis oxidation, the macrocycle M1 was dissolved in THF and treated with mild oxidant NaClO 2 in presence of scavenger 2-methyl-2-butene.…”

Section: Resultssupporting

confidence: 83%

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Post‐Synthesis Conversion of an Unstable Imine Cage to a Stable Cage with Amide Moieties Towards Selective Receptor for Fluoride

Bhandari

Mukherjee

2022

Chemistry A European J

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Synthesis of robust covalent macrocycles/cages via multiple amide‐bond forming reaction is highly challenging and generally it needs multistep reactions. One‐pot reaction of appropriate di‐/tri‐acyl chloride with a diamine generally results polymers or oligomers instead of discrete architectures. To overcome this limitation, a strategy is reported here using dynamic imine chemistry for facile construction of imine‐based macrocycle and cage upon treatment of a diamine with di‐ and tri‐aldehydes respectively, followed by post‐synthesis one‐step conversion of imine bonds to amides to form the desired robust macrocycle and cage containing multiple amide bonds. While the macrocycle was found to form aggregates in DMSO, the cage was intact without any aggregation. Six amide groups in the confined pocket of the cage made it an ideal receptor for selective binding of fluoride with very high selectivity (∼3 × ${\times }$ 103 fold) over chloride, and it was silent towards other halides, phosphate, and other oxyanions.

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Section: Resultssupporting

confidence: 83%

“…The imine‐based macrocycle ( M1 ) was synthesized using a modified reported procedure [16] . The obtained macrocycle was characterized by 1 H, 13 C NMR and IR spectroscopy where experimental data matched well with the reported results (Figures S3–S5).…”

Section: Resultssupporting

confidence: 75%

Post‐Synthesis Conversion of an Unstable Imine Cage to a Stable Cage with Amide Moieties Towards Selective Receptor for Fluoride

Bhandari

Mukherjee

2022

Chemistry A European J

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“…The presence of the gem‐dimethyl (GDM) group on amino acid derivatives has a noticeable impact on the cyclization process and the formation of conformationally locked polypeptides [52,53] . Inspired by these observations, we have chosen GDM‐substituted m‐xylenediamine in an imine condensation reaction to construct a highly constrained cage structure.…”

Section: Resultsmentioning

confidence: 99%

“…The presence of the gem-dimethyl (GDM) group on amino acid derivatives has a noticeable impact on the cyclization process and the formation of conformationally locked polypeptides. [52,53] Inspired by these observations, we have chosen GDM-substituted m-xylenediamine in an imine condensation reaction to construct a highly constrained cage structure. The target diamine (XA) was synthesized from bis-isocyanate substituted m-xylenediamine derivative via bis carbamate formation followed by hydrolysis with KOH (Scheme S1).…”

Section: Preparation Of Imine Cage and Model Compoundmentioning

confidence: 99%

Enhancing Fluorescence in Both Solution and Solid States Induced by Imine Cage Formation

Bhandari,

Ahmed,

Saha

et al. 2024

Chemistry A European J

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Developing luminescent materials that exhibit strong emissions in both solution and solid phases is highly desirable and challenging. Herein, we report imine‐bond directed formation of a rigid organic cage (TPE‐cage) that was synthesized by [2+4] imine condensation of a TPE‐cored tetra‐aldehyde (TPE‐TA) with a clip‐like diamine (XA) to illustrate confinement‐induced fluorescence enhancement. Compared to the non‐emissive TPE‐TA (ϕF=0.26 %) in the dichloromethane (DCM) solution, the TPE‐cage achieved a remarkable (~520‐fold) emission enhancement (ϕF=70.38 %). In contrast, a monomeric tetra‐imine model compound (TPE‐model) showed only a minor enhancement (ϕF=0.56 %) in emission compared to the parent tetra‐aldehyde TPE‐TA. The emission of TPE‐cage was further enhanced by ~1.5‐fold (ϕF=80.96 %) in the aggregated state owing to aggregation‐induced emission enhancement (AIEE). This approach establishes the potential for synthesizing luminescent materials with high emission in both solution and solid‐state by employing a single‐step imine condensation reaction.

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“…50 μl of acetic acid was added to the ACN solution and was kept undisturbed for 7 days to obtain pale yellow colored, needle-shaped crystals. A detailed synthesis of the IMC, macrocycle 10 is as reported [22]…”

Section: Molecular Crystallizationsmentioning

confidence: 99%

Structural and computational investigation of an imine-based propeller-shaped macrocyclic cage

et al. 2021

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In this study, we present the synthesis, spectroscopic and structural characterization of self-assembling gem-dimethyl imine based molecular cage (IMC). Self-assembling macrocycles and cages have well-defined cavities and have extensive functionalities ranging from energy storage, liquid crystals, and catalysts to water splitting photo absorber. IMC has large voids i.e., 25% of the total crystal volume thus could accommodate wide substrates. The synthesized imine-based molecular cages are stabilized by coaxial π bonded networks and long-range periodic van der Waal and non-bonded contacts as observed from the crystal structure. IMC also has typical properties of soft condensed matter materials, hence theoretical prediction of stress and strain tensor along with thermophysical properties were computed on crystal system and were found to be stable. Molecular dynamics revealed IMC is stabilized by, strong interactions between the interstitial phenyl rings. Density functional theory (DFT) based physicochemical properties were evaluated and has band gap of around 2.38ev (520 nm) similar to various photocatalytic band gap materials.

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Exploring the gem-dimethyl effect in the formation of imine-based macrocycles and cages

Abstract: A series of imine-based macrocycles and cages has been synthesized using the gem-dimethyl effect as a platform. Following this strategy, imine-based macrocyclization could be performed even at higher concentration.

Cited by 6 publications

References 31 publications

Post‐Synthesis Conversion of an Unstable Imine Cage to a Stable Cage with Amide Moieties Towards Selective Receptor for Fluoride

Post‐Synthesis Conversion of an Unstable Imine Cage to a Stable Cage with Amide Moieties Towards Selective Receptor for Fluoride

Enhancing Fluorescence in Both Solution and Solid States Induced by Imine Cage Formation

Structural and computational investigation of an imine-based propeller-shaped macrocyclic cage

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