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1.
Chem Asian J ; : e202400351, 2024 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-38700467

RESUMO

Polymers with all mechanically interlocked rings, such as linear [n]catenanes, have great potential as functional materials due to possible higher degrees of freedom that may contribute to their flexibility but remain elusive. All the synthetic methods used to prepare such a polymer yield mixtures of products. In the absence of higher molecular weight linear [n]catenanes, emphasis on synthesizing low molecular weight oligomers is being pursued. Here, we have described the synthesis of a linear [5]catenane by post-functionalizing a Co(III) templated [2]catenane having a pyridine-diamide unit free for further metal ion coordination. Two molecules were synthesized with suitable threading groups: one, two terminal azide groups, and two, with two terminal alkyne groups to form two [3]pseudorotaxane utilizing Co(III) coordination. These units were then joined, forming a macrocycle, using click reaction, giving the desired metallated linear [5]catenane in 40% yield. Removal of metal ions leads to linear [5]catenane. In addition, the formation of linear [3] and [2]catenane are also observed. All synthesized structures have been isolated by column chromatographic technique and characterized by 1H-NMR, 13C-NMR, and mass spectroscopy.

2.
Angew Chem Int Ed Engl ; : e202406272, 2024 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-38739535

RESUMO

Asymmetric wide-bandgap fullerene-free acceptors (FFAs) play a crucial role in organic solar cells (OSCs). Here, we designed and synthesized a simple asymmetric coumarin-anthracene conjugate named CA-CN with optical bandgap of 2.1 eV in a single-step condensation reaction. Single crystal X-ray structure analysis confirms various multiple intermolecular non-covalent interactions. The molecular orbital energy levels of CA-CN estimated from cyclic voltammetry were found to be suitable for its use as an acceptor for OSCs. Binary OSCs fabricated using CA-CN as acceptor and PTB7-Th as the donor achieve a power conversion efficiency (PCE) of 11.13%. We further demonstrate that the insertion of 20 wt% of CA-CN as a third component in ternary OSCs with PTB7-Th:DICTF as the host material achieved an impressive PCE of 14.91%, an improvement of ~43% compared to the PTB7-Th:DICTF binary device (10.38%). Importantly, the ternary blend enhances the absorption coverage from 400 to 800 nm and improves the morphology of the active layer. The findings highlight the efficacy of an asymmetric design approach for FFAs, which paves the way for developing high-efficiency OSCs at low cost.

3.
Chem Asian J ; 19(7): e202400031, 2024 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-38372572

RESUMO

Design and synthesis of higher order catenane are unexpectedly complex and involve precise cooperation among the precursors overcoming competing and opposing interactions. We achieved synthesis of [2], linear [3], radial [4] in a one-pot reaction by consecutive ring closing through click reactions. This synthesis gave three isolable products due to two, four, and six-click reactions between suitable coupling partners. Yields of the isolate templated-catenane decrease from lower to higher-ordered catenane (40 %, 12 %, and 4 %), probably due to the bite angle as well as the flexibility of the reacting partners. Removal of templating cobalt(III) ion leads to the formation of fully organic [2], linear [3], and radial [4]catenane. These synthesized catenanes were purified by column chromatography and characterized by 1H-NMR, 13C-NMR, and ESI-MS spectroscopy. The synthesized catenanes have free binding sites suitable for post-functionalization and may be used for the synthesis of higher-ordered catenane.

4.
Dalton Trans ; 52(42): 15549-15561, 2023 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-37753593

RESUMO

A series of coinage metal complexes bearing rarely explored ortho-silylated phosphine is reported. The treatment of diphenyl(2-(trimethylsilyl)phenyl)phosphine (1) with CuCl and [Cu(CH3CN)4]BF4 furnished the corresponding neutral [(1)CuCl]2 (2) and mono-cationic [(1)2Cu(CH3CN)]BF4 (3) complexes, respectively. The reactions of 1 with AgX (X = BF4-, NO3-) in 2 : 1 ratio furnished the corresponding mono cationic dicoordinate silver(I) complexes of the type [(1)2Ag]X (X = BF4- (4a), NO3- (4b)). The ortho-silylated phosphine ligand (1) was conveniently converted into the corresponding sulfide (5a) and selenide (5b) species, and their reactions with [Cu(CH3CN)4]BF4 yielded mono-cationic, homoleptic tris(silylphosphinochalcogenide)copper(I) complexes of the type [(5a/5b)3Cu]BF4 (6a/6b). The molecular structures of 2-4 and 6 were established by single-crystal X-ray diffraction analysis. The copper complexes 2, 3, and 6a were employed as catalysts in azide-alkyne cycloaddition reactions. Among these complexes, 3 was extensively used in the preparation of various mono- and bis-triazoles consisting of tolyl, benzyl, carbazolyl, and propargylic ether groups. Three sets of substituted triazole derivatives were achieved under mild conditions by employing copper(I) catalytic systems. The mechanistic studies indicated the formation of a heteroleptic copper(I) triazolide intermediate which was detected by high-resolution mass spectral analysis.

5.
Dalton Trans ; 52(44): 16151-16158, 2023 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-37603440

RESUMO

Two novel dicationic binuclear Cu(I) complexes of the type [{(BPPP)E2}Cu]2[BF4]2 (E = S (3a); Se (3b)) bearing (BPPP)E2 (BPPP = bis(diphenylphosphino)pyridine) pincer systems were isolated, and structurally characterized. The solid-state structures of 3a/3b display the presence of intermolecular cuprophilic (Cu⋯Cu) interactions between the two monocationic species, and consist of weak Cu⋯S bonding between the two cations. Besides, complex 3a was introduced as a molecular copper(I) catalyst in cyclization reactions, and new protocols were developed for the synthesis of a series of new oxazole and triazole derivatives bearing alkyne-phenyl propargylic ether substituents. 3a was also found to be active in achieving these two classes of heterocyclic compounds by the mechanical grinding method. One of the key intermediate copper-azide species was detected by the high-resolution mass spectrometry technique, which supports the proposed catalytic pathway. All the reported transformations were accomplished sustainably by employing a well-defined, earth-abundant, and cheap copper(I) catalytic system.

6.
Dalton Trans ; 52(26): 8850-8856, 2023 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-37338097

RESUMO

A structurally characterized porous Ag(I)-molecular cage AgMOC and a Cu(II)-coordination polymer CuCP with a pre-synthesized ligand 1,3-bis(((E)-2-methoxybenzylidene)amino)propan-2-ol and its parental amine with thiocyanate are reported to harness electrical mobility-driven hydrogen evolution activity. Porosity-induced electrically conductive AgMOC emerges as a better electrocatalyst with a Tafel slope of 104 mV per decade over Cu(II)-polymer's slope of 128 mV per decade. The electrochemical stability and durability of the designed electrocatalysts in harnessing the HER activity are also examined under experimental conditions.

7.
Dalton Trans ; 52(15): 4964-4972, 2023 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-36951181

RESUMO

The sustainable production of privileged amines by the catalytic reduction of nitriles with an inexpensive silane polymethylhydrosiloxane (PMHS) holds great promise to replace conventional synthetic routes that have limited applicability and involve the use of expensive metal catalysts. The use of late 3d-metal complexes provides an excellent platform for the rational design of inexpensive catalysts with exquisite control over their electronic and structural features through metal-ligand cooperativity. In this context, we have realistically designed two complexes based on nickel(II) and cobalt(II) with a redox-active imino-o-benzoquinonato ligand. The compounds were characterized by a suite of spectroscopic methods, cyclic voltammetry and single-crystal X-ray diffraction. Both complexes showed excellent catalytic activity in transforming various organonitriles into the corresponding primary amines selectively using the inexpensive PMHS. The catalytic performance of the complexes was evaluated by various control experiments and spectroscopic studies with detailed computational calculations revealing the crucial role of the non-innocent imino-o-benzoquinonato ligand and metal(II) ion cooperativity in controlling the reactivity and selectivity of the key metal-hydride intermediates in the course of catalytic reduction.

8.
Org Biomol Chem ; 17(10): 2824, 2019 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-30785172

RESUMO

Correction for 'Synthesis of medium-sized (6-7-6) ring compounds by iron-catalyzed dehydrogenative C-H activation/annulation' by Niranjan Panda et al., Org. Biomol. Chem., 2018, 16, 7861-7870.

9.
Org Biomol Chem ; 17(1): 74-82, 2018 12 19.
Artigo em Inglês | MEDLINE | ID: mdl-30478467

RESUMO

A novel green synthetic methodology has been developed to obtain enantiopure (2S)-2-C-spiro-glycosyl-3-nitrochromenes following the oxa-Michael-aldol condensation reaction of sugar derived 3-C-vinyl nitro olefins with substituted salicylaldehydes using Et3N as a base under neat conditions at rt-40 °C. The stereochemistry of the product is confirmed by a single crystal X-ray study. Several advantages are associated with this protocol such as cost effectiveness, easy accessibility, short reaction time, high yields, wide substrate scope and high enantiopurity.

10.
Org Biomol Chem ; 16(42): 7861-7870, 2018 10 31.
Artigo em Inglês | MEDLINE | ID: mdl-30303228

RESUMO

In this report, we have described a FeCl3-catalyzed process involving intramolecular annulation of o-phenoxy diarylacetylenes via hydroarylation to afford a series of biologically potent fused seven-membered (6-7-6) ring compounds under mild reaction conditions. This reaction was believed to proceed through Friedel-Crafts type sequential carbometallation followed by protonation to produce phenyldibenz[b,f]oxepines. This method was also extended to synthesize seven-membered rings that are fused with coumarins.

11.
Dalton Trans ; 43(33): 12564-73, 2014 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-25005871

RESUMO

Three novel tin(iv)corrole complexes have been prepared and characterized by various spectroscopic techniques including single crystal X-ray structural analysis. Packing diagrams of the tin(iv)corroles revealed that corrolato-tin(iv)-chloride molecules are interconnected by intermolecular C-HCl hydrogen bonding interactions. HCl distances are 2.848 Å, 3.051 Å, and 2.915 Å, respectively, for the complexes. In addition, the C-HCl angles are 119.72°, 144.70°, and 147.08°, respectively, for the complexes. It was also observed that in one of the three synthesized complexes dimers were formed, while in the other two cases 1D infinite polymer chains were formed. Well-defined and nicely organized three-dimensional hollow nanospheres (SEM images on silicon wafers) with diameters of ca. 676 nm and 661 nm are obtained in the complexes, forming 1D polymer chains. By applying a thin layer of tin(iv)corrole nanospheres to an ITO surface (AFM height images of ITO films; ∼200 nm in height), a device was fabricated with the following composition: Ag/ITO-coated glass/tin(iv)corrole nanospheres/ITO-coated glass/Ag. The resistivity (ρ) of the nanostructured film was calculated to be ∼2.4 × 10(8) Ω cm, which falls in the range of semi-insulating semiconductors. CAFM current maps at 10 V bias show bright spots with a 10-20 pA intensity and indicate that the nanospheres (∼250 nm in diameter) are the electron-conducting pathway in the device. The semi-insulating behavior arises from the non-facile electron transfer in the HOMOs of the tin(iv)corrole nanospheres.


Assuntos
Nanopartículas Metálicas/química , Nanosferas/química , Porfirinas/química , Compostos de Estanho/química , Cristalografia por Raios X
12.
Inorg Chem ; 53(3): 1417-29, 2014 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-24432714

RESUMO

Two novel trans-A2B-corroles and three [(corrolato){FeNO}(6)] complexes have been prepared and characterized by various spectroscopic techniques. In the native state, all these [(corrolato){FeNO}(6)] species are diamagnetic and display "normal" chemical shifts in the (1)H NMR spectra. For two of the structurally characterized [(corrolato){FeNO}(6)] derivatives, the Fe-N-O bond angles are 175.0(4)° and 171.70(3)° (DFT: 179.94°), respectively, and are designated as linear nitrosyls. The Fe-N (NO) bond distances are 1.656(4) Å and 1.650(3) Å (DFT: 1.597 Å), which point toward a significant Fe(III) → NO back bonding. The NO bond lengths are 1.159(5) Å and 1.162(3) Å (DFT: 1.162 Å) and depict their elongated character. These structural data are typical for low-spin Fe(III). Electrochemical measurements show the presence of a one-electron oxidation and a one-electron reduction process for all the complexes. The one-electron oxidized species of a representative [(corrolato){FeNO}(6)] complex exhibits ligand to ligand charge transfer (LLCT) transitions (cor(π) → cor(π*)) at 399 and 637 nm, and the one-electron reduced species shows metal to ligand charge transfer (MLCT) transition (Fe(dπ) → cor(π*)) in the UV region at 330 nm. The shift of the νNO stretching frequency of a representative [(corrolato){FeNO}(6)] complex on one-electron oxidation occurs from 1782 cm(-1) to 1820 cm(-1), which corresponds to 38 cm(-1), and on one-electron reduction occurs from 1782 cm(-1) to 1605 cm(-1), which corresponds to 177 cm(-1). The X-band electron paramagnetic resonance (EPR) spectrum of one-electron oxidation at 295 K in CH2Cl2/0.1 M Bu4NPF6 displays an isotropic signal centered at g = 2.005 with a peak-to-peak separation of about 15 G. The in situ generated one-electron reduced species in CH2Cl2/0.1 M Bu4NPF6 at 295 K shows an isotropic signal centered at g = 2.029. The 99% contribution of corrole to the HOMO of native species indicates that oxidation occurs from the corrole moiety. The results of the electrochemical and spectroelectrochemical measurements and density functional theory calculations clearly display a preference of the {FeNO}(6) unit to get reduced during the reduction step and the corrolato unit to get oxidized during the anodic process. Comparisons are presented with the structural, electrochemical, and spectroelectrochemical data of related compounds reported in the literature, with a particular focus on the interpretation of the EPR spectrum of the one-electron oxidized form.


Assuntos
Compostos Férricos/química , Porfirinas/química , Cristalografia por Raios X , Espectroscopia de Ressonância de Spin Eletrônica , Compostos Férricos/síntese química , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Oxirredução , Porfirinas/síntese química , Espectrofotometria Infravermelho , Espectrofotometria Ultravioleta
13.
Acta Crystallogr Sect E Struct Rep Online ; 67(Pt 5): m557, 2011 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-21754290

RESUMO

The centrosymmetric binuclear Cu(II) title complex, [Cu(2)(C(8)H(7)O(3))(4)(CH(3)CN)(2)], has a paddle-wheel-type structure [Cu-Cu distance = 2.6433 (3) Å]. Each Cu(II) ion is coordin-ated by four O atoms from two 3-meth-oxy-benzoate ligands and one acetonitrile N atom in a square-pyramidal geometry.

14.
Biochem Biophys Res Commun ; 378(3): 503-6, 2009 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-19032946

RESUMO

This paper reports self-assembly of a lysine conjugated with a biantennary mannose to form spherical structures. These supramolecular structures are found to be hollow in nature and they afford effective encapsulation of alkaline phosphatase enzyme, plasmid DNA and a GFP reporter gene, which was transfected in COS-7 cells. Loaded hollow structures also get disrupted upon mild sonication, releasing encapsulated molecules thereby illustrating their potential for confinement and delivery applications.


Assuntos
Técnicas de Transferência de Genes , Lisina/análogos & derivados , Lisina/química , Manose/química , Manosídeos/química , Animais , Células COS , Chlorocebus aethiops , Genes Reporter , Terapia Genética , Proteínas de Fluorescência Verde/genética , Lipossomos , Plasmídeos/genética , Plasmídeos/metabolismo , Sonicação
15.
Chem Commun (Camb) ; (22): 2526-8, 2008 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-18506232

RESUMO

We report synthesis and crystallographic studies of a ferrocenyl conjugate of adenine, where the hydrogen bonding interactions promote and stabilize nucleobase homotetrad formation.


Assuntos
Adenina/química , Compostos Ferrosos/química , Modelos Moleculares , Adenina/análogos & derivados , Adenina/síntese química , Cristalografia por Raios X , Ligação de Hidrogênio , Espectroscopia de Ressonância Magnética , Metalocenos , Conformação Molecular , Estrutura Molecular
16.
Inorg Chem ; 46(21): 8493-5, 2007 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-17854183

RESUMO

This Communication describes structures of a family of silver-adenine (purine) metallaquartets that occur in a four-stranded coordination motif, bearing a close resemblance to nucleic acid quadruplexes. Using modified purine frameworks, it is further demonstrated that subtle variations in nucleobase heterocycle are tolerable and a metallaquartet is obtained irrespective of the substitution, thus suggesting a high-propensity silver-adenine interaction to achieve quartet structures. All of the solid-state structures studied were orthorhombic, belonging to the Fdd2 space group.


Assuntos
Adenina/química , Química/métodos , Prata/química , Composição de Bases , Metais/química , Conformação Molecular , Estrutura Molecular , Purinas/química
17.
J Phys Chem B ; 111(30): 8680-3, 2007 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-17616223

RESUMO

Lone-pair...pi and, more recently, pi...pi interactions have been studied in small molecule crystal structures, and they are the focus of attention in some biomolecules. In this study, we have systematically analyzed 500 high-resolution protein structures (resolution < or =1.8 A) and identified 286 examples in which carbonyl oxygen atoms approach the aromatic centers within a distance of 3.5 A. Contacts involving backbone carbonyl oxygens are frequently observed in helices and, to some extent, in strands. Geometrical characterization indicates that these contacts have geometry in between that of an ideal pi...pi and a lone-pair...pi interaction. Quantum mechanical calculations using 6-311++G** basis sets reveal that these contacts give rise to energetically favorable interactions and, along with MD simulations, indicate that such interactions could stabilize secondary structures.


Assuntos
Carbono/química , Oxigênio/química , Proteínas/química , Aminoácidos Aromáticos/química , Benzeno/química , Formaldeído/química , Modelos Químicos
19.
Chemistry ; 13(1): 105-14, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-16991181

RESUMO

The synthesis and characterization of the first examples of core-modified corrole dimers linked through the meso positions are described. The dimers are obtained by a simple Ag(I)- or Fe(III)-catalyzed coupling reaction in near-quantitative yields. The corroles obtained are metalated with metal ions, such as Cu(II) and Ni(II). The electronic-absorption spectral studies reveal weak electronic interaction between the two subunits and the exciton coupling observed for the free-base corrole dimer (1717 cm(-1)) is lower than that for the corresponding protonated derivative (4081 cm(-1)). The solution-state structure derived from (1)H and two-dimensional NMR spectral studies reveals a noncoplanar arrangement of two corrole units. Geometry optimization at the B3LYP-631G level also confirms the noncoplanar arrangement of corroles with a dihedral angle of 64.8 degrees between two corrole planes. The electron paramagnetic resonance (EPR) and magnetic characterization studies on the paramagnetic copper-metalated dimer indicate that both copper ions behave as independent spins without any noticeable interaction. Results of fluorescence studies reveal a bathochromic shift of about 60 nm upon dimerization. The first hyperpolarizability (beta) measured by using the hyper Rayleigh scattering (HRS) method reveals doubling of the beta values on progressing from monomer to dimer, attributed to enhanced pi conjugation. The use of copper dimers in the photocleavage of DNA is also explored. It is shown that the bimetallic copper dimer selectively cleaves the nucleic acids without affecting the proteins, suggesting a possible application of the copper complex in the removal of nucleic acid contaminants from protein extracts through a simple photolytic pathway.


Assuntos
Reagentes de Ligações Cruzadas/química , Catálise , DNA/química , DNA/metabolismo , Dimerização , Eletroquímica , Elétrons , Ferro/química , Estrutura Molecular , Muramidase/metabolismo , Oxirredução , Fotólise , Porfirinas/química , Prata/química , Análise Espectral
20.
J Am Chem Soc ; 128(2): 400-1, 2006 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-16402813

RESUMO

This communication describes formation of a 3N-coordinated silver-modified adenine metallamacrocyclic quartet in solid state, its aggregative ordering on graphite surface, and luminescence.


Assuntos
Adenina/análogos & derivados , Compostos Macrocíclicos/química , Prata/química , Adenina/química , Óxidos N-Cíclicos , Luminescência , Microscopia de Força Atômica , Modelos Moleculares , Conformação de Ácido Nucleico , Compostos Organometálicos/química
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