Acute detection of assorted classes of organo-toxins under practical environment is an important sustainable agenda, whereas cooperative and recyclable catalysis can mitigate hazards by minimizing energy requirements, and reducing waste generation.1 We constructed an acid-base stable Co(II)-framework (CSMCRI-10), wherein unidirectional porous channels are decorated by anionic [Co2(µ2-OH)(COO)4(H2O)3] secondary building units and neutral [CoN2(COO)2] nodes.2 Intense luminescence signature of the hydrolytically robust framework is harnessed in selective, fast-responsive and regenerable detection of two detrimental organo-aromatics, 4-aminophenol (4-AP) and 2,4,6-trinitrophenol (TNP). Benefitting from concurrent existences of open-metal site and triphenylamine moiety functionalized ligand, the activated framework acts as outstandingly cooperative heterogeneous catalyst in deacetalization-Knoevenagel condensation under mild condition.3 The acid-base dual catalysis is first-time detailed from combined inputs of control experiments and DFT validations. To the best of tandem reaction, larger-sized substrate exhibits insignificant conversion, and certifies rarest pore-fitting induced size-selectivity.
1. Kreno, L. E.; Leong, K.; Farha, O. K.; Allendorf, M.; Van Duyne, R. P.; Hupp, J. T. Chem. Rev. 2012, 112, 1105.
2. Seal, N.; Palakkal, A. S.; Singh, M.; Goswami, R. ; Pillai, R. S.; Neogi, S. ACS Applied Materials & Interfaces 2021, 13, 28378.
3. Yao, C.; Zhou, S.; Kang, X.; Zhao, Y.; Yan, R.; Zhang, Y.; Wen, L. Inorg. Chem. 2018, 57, 11157.

A Chemo-robust Bifunctional Co(II)-MOF for Trace Detection of Assorted Organo-Toxins and Highly Cooperative deacetalization-Knoevenagel Condensation with Pore-Fitting Induced Size-Selectivity

Covalent organic frameworks (COFs) are burgeoning class of crystalline porous material that attracted much attention because of their enormous structural diversity, and tunable pore sizes.1 Especially, applications that aim unravelling environmental issues have surfaced as hottest research areas as a result of their task-specific pore structure modulation.2 In particular, exploring their dynamic behaviour upon exposure to external stimuli is likely to enable unprecedented switchable gas adsorption. From catalytic viewpoint, developing new methodology for constructing carbon–carbon bonds will overwhelmingly dictate the efficacy of organic synthesis, wherein heterogenization of active catalyst over COF backbone could benefit size-selective cross coupling reaction under green reaction conditions. Building on these, we developed an imine-based, diamondoid COF with free N-atom decorated pore-wall that displays selective and multicyclic CO2 adsorption along with solvent-assisted reversible structural dynamism, which triggers unprecedented CO2 adsorption switch.2 Post-synthetic hooking of homogeneous photocatalyst benefits devising first-ever Ru(Bpy)32+ hooked 3D COF (Ru-COF) that performs visible-light mediated, oxidative photocyanation of tertiary amines using molecular oxygen at room temperature in H2O. To the best of Ru-COF, atom-economic photocyanation is realized via in situ generated iminium ion, where larger substrates exhibit insignificant conversion to α-aminonitriles, and validates rarest pore-fitting-induced size selectivity in oxidative Strecker reaction.3
References and Notes:
1. Song, Y.; Sun, Q.; Aguila, B.; Ma, S.; Adv. Sci., 2019, 6, 1970011.
2. (a)Sasmal, H. S.; Halder, A.; Kunjattu, H. S.; Dey, K.; Nadol, A.; Ajithkumar, T. G.; Ravindra Bedadur, P.; Banerjee, R.; J. Am. Chem. Soc., 2019, 141 (51), 20371−20379. (b) Dey, K.; Kunjattu H, S.; Chahande, A. M.; Banerjee, R.; Angew. Chem., Int. Ed., 2020, 59, 1161−1165.
3. Kumar, G.; Singh, M.; Goswami, R.; Neogi, S.; ACS Appl. Mater. Interfaces, 2020, 12, 48642–48653.

Structural Dynamism Triggered Switchable CO2 Adsorption and Visible-light Mediated Size Selective Cα–H Photocyanation in Pre-functionalized Covalent Organic Framework

Synthesis of heterocycles using transition-metal catalyzed C-H activation/annulation reactions has been very well recognised as one of the most powerful methods in modern synthetic organic chemistry.1 Our group is involved in functionalization of N-methoxy benzamide for the synthesis of novel organic molecules.2,3 The synthesis of hydroxyl Isoindolones by Pd/Cu-BNP catalyzed amide group directing ortho C-H activation/annulation reactions of N-methoxy benzamide with benzaldehyde in presence of aqueous TBHP as oxidant in 1,4-dioxane solvent at 100 oC in presence of molecular oxygen is described. 4 Both N-methoxy benzamide substituted with electron-donating as well as electron-withdrawing groups and benzaldehyde are well tolerated to provide hydroxyl Isoindolones in moderate to good yields. This methodology has highly functional group tolerance and no additional ligand and additive required. The Pd/Cu-BNP catalyst has been recovered and reused up to five catalytic cycles without any significant loss of its catalytic activity and yield.

An Efficient Pd/Cu-BNP Bimetallic Nanoparticles Catalyzed Synthesis of
Hydroxyl Isoindolones by C-H Activation and Annulation

Thermosets from environment-friendly sources with good thermal stability and flame-resistant characteristics without compromising their mechanical properties are highly desired. In this work, an upcoming class of bio-based benzoxazine monomer C-a and C-trisapm [agrowaste sourced cardanol (C) with aniline (a) or tris-p-aminophenylmethane (trisapm)] was polymerized at low temperature using a non-toxic bio-based phytic acid (PA) at two weight ratios (5 and 10 wt/wt%). The pristine polymer C-a, C-trisapm and its blends with PA were characterized using energy dispersive X-ray (EDX), scanning electron microscopy (SEM), FTIR, 1H-, 31P-NMR spectroscopy to support covalent tethering of PA and homogeneous distribution within the polymer network. The polymerization kinetics was monitored by NMR and FTIR and formation of thermally mediated cross-linked network poly(C-a)/poly(C-trisapm) formation was studied by differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA), respectively. Rheological variation and adhesive strength of the polymers was determined by rheometer and lap shear strength (LSS) measurements. Pristine poly(C-trisapm) revealed better thermal stability and mechanical properties than poly(C-a) which is accounted to the higher crosslinking density of the former. At a phosphorous content of 1.4% and 2.8% in poly(C-a) the resultant thermosets scored a V0 rating (in UL 94 test), a LOI (24.3% and 26%), and low smoke density values, better than poly(C-a). To understand the mechanism of flame retardance behaviour, the char residue of composites was analyzed by digital photos, scanning electron microscopy (SEM), and FTIR spectroscopy. Existence of an effective condensed-phase mechanism contributed to the flame retardancy in the composites. PA served the dual purpose both as an initiator for ring-opening polymerization of benzoxazine monomer and to impart the flame retardant properties. This is due to the high phosphorus content and acidic hydroxyl groups in PA. This study demonstrates that phytic acid is a potential FR halogen-free biobased chemical which can be utilized as a versatile platform for fabricating high-performance thermoset polymers with excellent comprehensive properties.

Biosourced Phytic acid as a Greener Flame retardant for Cardanol based polybenzoxazine network

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27th CRSI National Symposium in Chemistry

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