Pyrene-Based Nanoporous Covalent Organic Framework for Carboxylation of C-H Bonds with CO2 and Value-Added 2-Oxazolidinones Synthesis under Ambient Conditions

The selective carbon capture and utilization (CCU) as a one-carbon (C1) feedstock offers dual advantages for mitigating the rising atmospheric CO2 content and producing fine chemicals/fuels. In this context, herein, we report the application of a porous bipyridine-functionalized, pyrene-based covalent organic framework (Pybpy-COF) for the stable anchoring of catalytic Ag(0) nanoparticles (NPs) and its catalytic investigation for fixation of CO2 to commodity chemicals at ambient conditions. Notably, Ag@Pybpy-COF showed excellent catalytic activity for the carboxylation of various terminal alkynes to corresponding alkynyl carboxylic acids/phenylpropiolic acids via C-H bond activation under atmospheric pressure conditions. Besides, carboxylative cyclization of various propargylic amines with CO2 to generate 2-oxazolidinones, an important class of antibiotics, has also been achieved under mild conditions. This significant catalytic activity of Ag@Pybpy-COF with wide functional group tolerance is rendered by the presence of highly exposed, alkynophilic Ag(0) catalytic sites decorated on the pore walls of high surface area (787 m2 g-1) Pybpy-COF. Further, density functional theory calculations unveiled the detailed mechanistic path of the Ag@Pybpy-COF-catalyzed transformation of CO2 to alkynyl carboxylic acids and 2-oxazolidinones. Moreover, the catalyst showed high recyclability for several cycles of reuse without significant loss in its catalytic activity and structural rigidity. This work demonstrates the promising application of Pybpy-COF for stable anchoring of Ag NPs for successful transformation of CO2 to valuable commodity chemicals at ambient conditions.

Design of porphyrin-based frameworks for efficient visible light-promoted reduction of CO2 from dilute gas: Combined experimental and theoretical investigation

The photocatalytic carbon dioxide reduction (CO2R) coupled with hydrogen evolution reaction (HER) constitutes a promising step for a sustainable generation of syngas (CO + H2), an essential feedstock for the preparation of several commodity chemicals. Herein, visible light/sunlight-promoted catalytic reduction of CO2 and protons to syngas using rationally designed porphyrin-based 2D porous organic frameworks, POF(Co/Zn) is demonstrated. Indeed, POF(Co) showed superior catalytic performance over the Zn counterpart with CO and H2 generation rates of 1104 and 3981 μmol g-1h-1, respectively. The excellent catalytic performance of Co-based POF is aided by the favorable transfer of photo-excited electrons from Ru-sensitizer to the CoII catalytic site, which is not feasible in the case of POF(Zn), revealed from the theoretical investigation. More importantly, the POF(Co) catalyzes the reduction of CO2 even from dilute gas (13% CO2), surpassing most reported framework-based photocatalytic systems. Significantly, the catalytic performance of POF(Co) was increased under natural sunlight conditions suggesting sunlight-promoted enhancement in syngas generation. The in-depth theoretical investigation further unveiled the comprehensive mechanistic pathway of the light-promoted concurrent CO and H2 generation. This work showcases the advantages of porphyrin-based frameworks for visible light/sunlight-promoted syngas generation by utilizing greenhouse gas (CO2) and protons under mild eco-friendly conditions.

Fe(III)-Anchored Porphyrin-Based Nanoporous Covalent Organic Frameworks for Green Synthesis of Cyclic Carbonates from Olefins and CO2 under Atmospheric Pressure Conditions

The utilization of carbon dioxide (CO2) as a C1 source coupled with olefins, readily accessible feedstocks, offers dual advantages of mitigating atmospheric carbon dioxide and green synthesis of valuable chemicals. In this regard, herein we demonstrate the application of Fe(III)-anchored porphyrin-based covalent organic framework (P-COF) as a promising recyclable catalyst for one-step generation of cyclic carbonates (CCs), value-added commodity chemicals from olefins and CO2, under mild atmospheric pressure conditions. Moreover, this one-pot synthesis was applied to transform various olefins (aliphatic and aromatic) into the corresponding CCs in good yield and selectivity. In addition, the Fe(III)@P-COF showed good recyclability and durability for multiple reuse cycles without losing its catalytic activity. Notably, this one-step synthesis strategy presents an eco-friendly, atom-economic alternative to the conventional two-step process requiring epoxides. This work represents a rare demonstration of porphyrin COF-catalyzed one-pot CC synthesis by utilizing readily available olefins at atmospheric pressure of carbon dioxide.

Ionic Fe(III)-porphyrin frameworks for one-pot synthesis of cyclic carbonates from olefins and CO2

In this study, rational construction of FeIII-centered porphyrin-based bifunctional ionic porous organic polymers (Fe-IPOP1/2) for one-step, halogen-free, cascade transformation of olefins and CO2 to cyclic carbonates over conventional two-step process...

Strategic Design of Mg-Centered Porphyrin Metal-Organic Framework for Efficient Visible Light-Promoted Fixation of CO2 under Ambient Conditions: Combined Experimental and Theoretical Investigation

The sunlight-driven fixation of CO2 into valuable chemicals constitutes a promising approach toward environmental remediation and energy sustainability over traditional thermal-driven fixation. Consequently, in this article, we report a strategic design and utilization of Mg-centered porphyrin-based metal-organic framework (MOFs) having relevance to chlorophyll in green plants as a visible light-promoted highly recyclable catalyst for the effective fixation of CO2 into value-added cyclic carbonates under ambient conditions. Indeed, the Mg-centered porphyrin MOF showed good CO2 capture ability with a high heat of adsorption (44.5 kJ/mol) and superior catalytic activity under visible light irradiation in comparison to thermal-driven conditions. The excellent light-promoted catalytic activity of Mg-porphyrin MOF has been attributed to facile ligand-to-metal charge transfer transition from the photoexcited Mg-porphyrin unit (SBU) to the Zr6 cluster which in turn activates CO2, thereby lowering the activation barrier for its cycloaddition with epoxides. The in-depth theoretical studies further unveiled the detailed mechanistic path of the light-promoted conversion of CO2 into high-value cyclic carbonates. This study represents a rare demonstration of sunlight-promoted sustainable fixation of CO2, a greenhouse gas into value-added chemicals.

Design of noble metal-free CoTiO3/Zn0.5Cd0.5S heterostructure photocatalyst for selective synthesis offurfuraldehyde combined withH2production

The development of photocatalytic systems composed of earth-abundant metal-based catalysts for efficient production of clean fuel, H₂ as well as value-added chemicals is of significant importance towards sustainable generation of energy resources. Consequently, herein we report rational construction of Z-scheme CoTiO₃/xZn_0.5Cd_0.5S (x = 5 (S1), 10 (S2), 15 (S3) and 20 wt% (S4)) heterostructures featuring suitable band structure for efficient photocatalytic reduction of protons of water to H₂ combined with selective oxidation of furfuryl alcohol (biomass derivative) to a value-added product, furfuraldehyde. Electron microscopy analysis of heterostructure S2 revealed that Zn_0.5Cd_0.5S nanoparticles are decorated over the surface of CoTiO₃ microrods. The photocatalytic studies showed higher catalytic performance by S2, for selective oxidation of furfuryl alcohol to furfuraldehyde with 95% yield coupled with a H₂ generation rate of 1929 μmol g^-1h^-1 which is about 4-fold higher than that of pristine Zn_0.5Cd_0.5S. The enhanced catalytic performance of heterostructure S2 has been ascribed to synergistic interaction aided by the Z-scheme heterojunction formation between CoTiO₃ and Zn_0.5Cd_0.5S. Overall, this work demonstrates the application of noble metal-free photocatalyst for simultaneous production of H₂ and value-added chemical under mild and environment-friendly conditions.

Strategic design of a bifunctional Ag(i)-grafted NHC-MOF for efficient chemical fixation of CO2 from a dilute gas under ambient conditions

Facile grafting of catalytically active Ag(i) into CO2-philic NHC-MOF for simultaneous capture and conversion of CO2 from dilute gas to value-added α-alkylidene cyclic carbonate and oxazolidinones under mild conditions is demonstrated.

Acylation of oxindoles using methyl/phenyl esters via the mixed Claisen condensation - an access to 3-alkylideneoxindoles

Predominantly, aggressive acid chlorides and stoichiometric coupling reagents are employed in the acylating process for synthesizing carbonyl tethered heterocycles. Herein, we report simple acyl sources, viz. methyl and phenyl esters, which acylate oxindoles via the mixed Claisen condensation. This straightforward protocol is mediated by LiHMDS and KOtBu and successfully applied to a wide range of substrates. It is a noteworthy transformation that skips the stepwise generation of enolates and acylation, and the reaction is performed at a moderate temperature with no side reactions. This protocol produces the first examples of ortho-substituents in an aryl ring flanked with electron-donating and electron-withdrawing substrates. Interestingly, robust organometallic ferrocenyl methyl ester cleaved under these conditions with ease. Furthermore, biologically important Tenidap's analog was synthesized by this protocol.

Construction of 3D lanthanide based MOFs with pores decorated with basic imidazole groups for selective capture and chemical fixation of CO2

Rational construction of three new 3D lanthanide-based MOFs exhibiting selective CO₂ capture and conversion to value-added cyclic carbonates under mild conditions is reported.

Highly efficient visible-light-driven reduction of Cr(vi) from water by porphyrin-based metal–organic frameworks: effect of band gap engineering on the photocatalytic activity

Highly efficient visible-light-assisted photocatalytic reduction of Cr(vi) to Cr(iii) from aqueous phase using Zr(iv)-porphyrin MOFs, Zr₆(μ₃-OH)₈(OH)₈(MTCPP)₂, (PCN-222(M)) (M = H₂, Zn^II, Cu^II, Ni^II, Co^II, Fe^IIICl, and Mn^IIICl) is presented.

Construction of a bifunctional Zn(ii)–organic framework containing a basic amine functionality for selective capture and room temperature fixation of CO2

The construction of a novel 3D, porous, bifunctional Zn(ii)–organic framework featuring two-types of 1D channels for efficient fixation of CO₂ to cyclic carbonates under solvent-free mild conditions of RT is reported.

Construction of a 3D porous Co(ii) metal–organic framework (MOF) with Lewis acidic metal sites exhibiting selective CO2 capture and conversion under mild conditions

The application of a 3D Co(ii)-MOF as a recyclable heterogeneous catalyst for conversion of CO₂ to cyclic carbonates is reported.

Photochemical oxidation of water catalysed by cyclometalated Ir(iii) complexes bearing Schiff-base ligands

Synthesis, characterization and photochemical oxidation of water catalysed by cyclometalated Ir(iii) complexes bearing Schiff-base ligands in the presence of Na₂S₂O₈ and [Ru(bpy)₃]²⁺ as a PS has been demonstrated.

Construction of bifunctional 2-fold interpenetrated Zn(ii) MOFs exhibiting selective CO2 adsorption and aqueous-phase sensing of 2,4,6-trinitrophenol

Design of Zn(ii) MOFs, [{Zn(BINDI)_0.5(bpa)_0.5(H₂O)}·4H₂O]_n (MOF1) and [{Zn(BINDI)_0.5(bpe)}·3H₂O]_n (MOF2) for selective CO₂ storage and aqueous-phase detection of TNP is demonstrated.

Substrate-Independent Epitaxial Growth of the Metal-Organic Framework MOF-508a

Plasmachemical deposition is a substrate-independent method for the conformal surface functionalization of solid substrates. Structurally well-defined pulsed plasma deposited poly(1-allylimidazole) layers provide surface imidazole linker groups for the directed liquid-phase epitaxial (layer-by-layer) growth of metal-organic frameworks (MOFs) at room temperature. For the case of microporous [Zn (benzene-1,4-dicarboxylate)-(4,4'-bipyridine)_0.5] (MOF-508), the MOF-508a polymorph containing two interpenetrating crystal lattice frameworks undergoes orientated Volmer-Weber growth and displays CO₂ gas capture behavior at atmospheric concentrations in proportion to the number of epitaxially grown MOF-508 layers.

Ruthenium(ii) arene NSAID complexes: inhibition of cyclooxygenase and antiproliferative activity against cancer cell lines

Ru(ii)–arene complexes with NSAIDs as co-ligands show marked antiproliferative activity against cancer cell lines along with cyclooxygenase inhibition properties.

Construction of 3D homochiral metal–organic frameworks (MOFs) of Cd(ii): selective CO2adsorption and catalytic properties for the Knoevenagel and Henry reaction

Syntheses of two new homochiral, 3D metal–organic frameworks (MOFs) of Cd(ii) and the selective CO₂adsorption and catalytic properties of1has been demonstrated.

Sulfonamide vs. sulfonimide: tautomerism and electronic structure analysis of N-heterocyclic arenesulfonamides

Experimental and computational studies suggest a preference toward the sulfonimide tautomer in N-heterocyclic arenesulfonamide.

Synthesis, crystal structure and water oxidation activity of [Ru(terpy)(bipy)Cl]+ complexes: influence of ancillary ligands on O2 generation

Synthesis of four new complexes [Ru^II(MeMPTP)(bpy)Cl]PF₆ (1), [Ru^II(MeMPTP)(dmbpy)Cl]PF₆ (2), [Ru^II(MeMPTP)(dmdcbpy)Cl]PF₆ (3) and [Ru^II(MeMPTP)(Pic)₂Cl]PF₆ (4) and their catalytic activity for chemical oxidation of water into O₂ generation has been demonstrated.

Design, structures and study of non-covalent interactions of mono-, di-, and tetranuclear complexes of a bifurcated quadridentate tripod ligand, N-(aminopropyl)-diethanolamine

Supramolecular non-covalent interactions in novel mono-, di- and tetranuclear complexes are explored.

Synthesis and photophysics of extended π-conjugated systems of substituted 10-aryl-pyrenoimidazoles

The synthesis of π-extended 10-aryl-pyrenoimidazoles having different substituents was realised via Ru(ii)-catalyzed oxidative annulation of 10-aryl-pyrenoimidazole with diphenylacetylene. The single crystal X-ray structure of trifluoromethyl and carboxylate substituted annulated-10-aryl-pyrenoimidazoles confirms the near coplanarity of the pyrene and imidazole moieties and the presence of twisted conformation resulting in intermolecular C-Hπ interactions. The lowest energy absorption maximum becomes red-shifted characteristic to the nature of the substituent owing to the extended π-conjugation, and specifically the nitro substituent shows intense absorption in the visible region with the maximum at 440 nm. All the molecules were found to show intense fluorescence both in solution and solid states. Strikingly, 170 nm red-shifted fluorescence with a large Stokes shift ca. 7000 cm^-1 for the nitro derivative, a value nearly two-fold higher than the parent compound despite its rigid polyaromatic skeleton was observed. The combination of electron rich π-conjugated aromatic systems with electron deficient substituents induces the intramolecular charge transfer interactions, which has been corroborated with the theoretical calculations.

Visible-Light-Assisted Photocatalytic Reduction of Nitroaromatics by Recyclable Ni(II)-Porphyrin Metal-Organic Framework (MOF) at RT

A microporous Ni(II)-porphyrin metal-organic framework (MOF), [Ni3(Ni-HTCPP)2(μ2-H2O)2(H2O)4(DMF)2]·2DMF, (MOF1) (where, Ni-HTCPP = 5,10,15,20-tetrakis(4-benzoate) porphyrinato-Ni(II)) has been synthesized by the solvothermal route. Single-crystal X-ray diffraction study of 1 reveals a 2D network structure constituted by Ni3 cluster and [Ni-HTCPP](3-) metalloligand having (3, 6)-connected binodal net with {4(3)}2{4(6)·6(6)·8(3)}-kgd net topology. The 2D layers are further stacked together through π-π interactions between the porphyrin linkers to generate a 3D supramolecular framework which houses 1D channels with dimension of ∼5.0 × 9.0 Å(2) running along the crystallographic a-axis. Visible-light-assisted photocatalytic investigation of MOF1 for heterogeneous reduction of various nitroaromatics at room temperature resulted in the corresponding amines with high yield and selectivity. On the contrary, the Ni(II)-centered porphyrin tetracarboxylic acid [Ni-H4TCPP] metalloligand does not show the photocatalytic activity under similar conditions. The remarkably high catalytic performance of MOF1 over [Ni-H4TCPP] metalloligand has been attributed due to cooperative catalysis involving the Ni-centered porphyrin secendary building units (SBUs) and the Ni3-oxo node. Further, the MOF1 was recycled and reused up to three cycles without any significant loss of catalytic activity as well as structural rigidity. To the best of our knowledge, MOF1 represents the first example of MOF based on 3d metal ion exhibiting visible-light-assisted reduction of nitroaromatics under mild conditions without the assistance of noble metal cocatalysts.

Expedient synthesis of new cinnoline diones by Ru-catalyzed regioselective unexpected deoxygenation-oxidative annulation of propargyl alcohols with phthalazinones and pyridazinones

Ruthenium-catalyzed simple, cascade and one-pot synthesis of cinnoline-fused diones has been carried out by the C–H activation of phthalazinones/pyridazinones.

Fine tuning through valence bond tautomerization of ancillary ligands in ruthenium(ii) arene complexes for better anticancer activity and enzyme inhibition properties

Novel valence tautomerized ancillary ligand induce antiproliferative activity in ruthenium complex.

Green synthesis, optical and magnetic properties of a MnIImetal–organic framework (MOF) that exhibits high heat of H2adsorption

Green synthesis of a 3D, Mn(ii) MOF, [Mn₃(NDC)₃(DMA)₄]n(1) has been achieved by employing mechanochemical and sonochemical routes and1′exhibits an interesting gas uptake properties with a high value of isosteric heat of adsorption (Q_st) for H₂.

Template-free syntheses of hierarchical PbS microstructures using a new sulphur source and their time-dependent morphological evolution and photocatalytic properties

Template-free PbS microstructures composed of nanocrystals exhibiting time-dependent morphological evolution from cubes to dendrites were synthesised by one-pot solvothermal route using DBDS as a new temperature controlled in situ source of S²⁻ ions.

Construction of 2D interwoven and 3D metal–organic frameworks (MOFs) of Cd(ii): the effect of ancillary ligands on the structure and the catalytic performance for the Knoevenagel reaction

The effect of ancillary ligands on structure and catalytic activity for Knoevenagel reaction of three new metal–organic coordination networks of Cd(ii) constructed from a rigid dicarboxylate ligand and various bipyridine spacers has been presented.

Regioselective synthesis of a vitamin K3 based dihydrobenzophenazine derivative: its novel crystal structure and DFT studies

A novel regioselective synthesis of vitamin K3 based dihydrobenzophenazine is reported.

One-pot, template-free syntheses of spherical ZnS nanocrystals using a new S2−source and their photocatalytic study

A facile, one-pot solvothermal method for the syntheses of template-free ZnS NCs (~3–6 nm) using (C₇H₇)S₂as a newin situsource of S²⁻ions without and with the use of MCE-capping agent has been demonstrated. Photocatalytic investigation of the NCs revealed very good activity for degradation of MO under UV light irradiation.

A luminescent 3D interpenetrating metal–organic framework for highly selective sensing of nitrobenzene

A three-dimensional (3D), luminescent, 5-fold interpenetrating metal–organic framework (MOF), [Zn₂(fdc)₂(bpee)₂(H₂O)·2H₂O] (1) exhibiting highly selective sensing of nitrobenzene (NB) via a fluorescence quenching mechanism has been demonstrated.

Construction of 2D interwoven and 3D interpenetrated metal–organic frameworks of Zn(ii) by varying N,N′-donor spacers

Four new MOFs of Zn(ii) with different degrees of interpenetration have been synthesized using trans,trans-muconic acid and different N,N′-donors.

Template-free syntheses of CdS microspheres composed of ultrasmall nanocrystals and their photocatalytic study

A one-pot, template-free, solvothermal method for synthesizing CdS microspheres composed of ultrasmall (∼2 nm) nanocrystals without and with the use of MCE-capping agent has been developed. The photocatalytic activity of the microspheres for degradation of MO under UV and natural sunlight irradiation has been compared.