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1.
Chemistry ; 30(1): e202302971, 2024 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-37870299

RESUMO

In this study, we explore feasibility of the mechanochemical approach in the synthesis of tetrabenzofluorenes (fluoreno[5]helicenes). For this, commercially available phenylated cyclopentadiene precursors are subjected to the Scholl reaction in the solid state using FeCl3 as an oxidant and sodium chloride as the solid reaction medium. This ball milling process gave access to the 5-membered ring containing-helicenes in one synthetic step in high (95-96 %) isolated yields. The solution-phase reactions, however, were found to be moderate to low yielding in this regard (10-40 %).

2.
Chemistry ; : e202402056, 2024 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-38962947

RESUMO

The synthesis of new compounds is an important pillar for the advancement of the field of chemistry and adjacent fields. In this regard, over the last decades huge efforts have been made to not only develop new molecular entities but also more efficient sustainable synthetic methodologies due to the increasing concerns over environmental sustainability. In this context, we have developed synthetic routes to novel corannulene flanked imidazolium bromide NHC precursors both in the solid-state and solution phases. Our work presents a comprehensive comparative study of mechanochemical routes and conventional solution-based methods. Green metrics and energy consumption comparison were performed for both routes revealing ball-milling generation of these compounds to be an environmentally greener technique to produce such precursors compared to conventional solvent-based methods. In addition, we have demonstrated proof-of-concept of the herein reported corannulene flanked NHCs to be robust ligands for transition metals and their ligand substitution reactions.

3.
J Am Chem Soc ; 145(23): 12475-12486, 2023 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-37267593

RESUMO

Artificial molecular machines have captured the full attention of the scientific community since Jean-Pierre Sauvage, Fraser Stoddart, and Ben Feringa were awarded the 2016 Nobel Prize in Chemistry. The past and current developments in molecular machinery (rotaxanes, rotors, and switches) primarily rely on organic-based compounds as molecular building blocks for their assembly and future development. In contrast, the main group chemical space has not been traditionally part of the molecular machine domain. The oxidation states and valency ranges within the p-block provide a tremendous wealth of structures with various chemical properties. Such chemical diversity─when implemented in molecular machines─could become a transformative force in the field. Within this context, we have rationally designed a series of NH-bridged acyclic dimeric cyclodiphosphazane species, [(µ-NH){PE(µ-NtBu)2PE(NHtBu)}2] (E = O and S), bis-PV2N2, displaying bimodal bifurcated R21(8) and trifurcated R31(8,8) hydrogen bonding motifs. The reported species reversibly switch their topological arrangement in the presence and absence of anions. Our results underscore these species as versatile building blocks for molecular machines and switches, as well as supramolecular chemistry and crystal engineering based on cyclophosphazane frameworks.

4.
Chemistry ; 29(18): e202203856, 2023 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-36598176

RESUMO

Herein we show that hybridisation of buckybowl corannulene and thiophene-S,S-dioxide motifs is a general approach for the preparation of high electron affinity molecular materials. The devised synthesis is modular and relies on thienannulation of corannnulene-based phenylacetylene scaffolds. The final compounds are highly soluble in common organic solvents. These compounds also exhibit interesting optical properties such as absorption and emission in the blue/green regions of the electromagnetic spectrum. Importantly, a bis-S,S-dioxide derivative exhibits three reversible reductions similar in their strength to the prevalent fullerene-based electron acceptor phenyl-C61 -butyric acid methyl ester (PC61 BM).

5.
Acc Chem Res ; 54(13): 2858-2870, 2021 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-34115472

RESUMO

This Account describes a body of research in the design and synthesis of molecular materials prepared from corannulene. Corannulene (C20H10) is a molecular bowl of carbon that can be visualized as the hydrogen-terminated cap of buckminsterfullerene. Due to this structural resemblance, it is often referred to as a buckybowl. The bowl can invert, accept electrons, and form host-guest complexes. Due to these characteristics, corannulene presents a useful building block in materials chemistry.In macromolecular science, for example, assembly of amphiphilic copolymers carrying a hydrophobic corannulene block enables micelle formation in water. Such micellar nanostructures can host large amounts of fullerenes (C60 and C70) in their corannulene-rich core through complementarity of the curved π-surfaces. Covalent stabilization of the assembled structures then leads to the formation of robust water-soluble fullerene nanoparticles. Alternatively, use of corannulene in a polymer backbone allows for the preparation of electronic and redox-active materials. Finally, a corannulene core enables polymer chains to respond to solution temperature changes and form macroscopic fibrillar structures. In this way, the corannulene motif brings a variety of properties to the polymeric materials.In the design of non-fullerene electron acceptors, corannulene is emerging as a promising aromatic scaffold. In this regard, placement of sulfur atoms along the rim can cause an anodic shift in the molecular reduction potential. Oxidation of the sulfur atoms can further enhance this shift. Thus, a variation in the number, placement, and oxidation state of the sulfur atoms can create electron acceptors of tunable and high strengths. An advantage of this molecular design is that material solubility can also be tuned. For example, water-soluble electron acceptors can be created and are shown to improve the moisture resistance of perovskite solar cells.Host-guest complexation between corannulene and γ-cyclodextrin under flow conditions of a microfluidic chamber allows for the preparation of water-soluble nanoparticles. Due to an oligosaccharide-based sugarcoat, the nanoparticles are biocompatible while the corannulene component renders them active toward nonlinear absorption and emission properties. Together, these attributes allow the nanoparticles to be used as two-photon imaging probes in cancer cells.Finally, aromatic extension of the corannulene nucleus is seen as a potential route to nonplanar nanographenes. Typically, such endeavors rely upon gas-phase synthesis or metal-catalyzed coupling protocols. Recently, two new approaches have been established in this regard. Photochemically induced oxidative cyclization, the Mallory reaction, is shown to be a general method to access corannulenes with an extended π-framework. Alternatively, solid-state ball milling can achieve this goal in a highly efficient manner. These new protocols bring practicality and sustainability to the rapidly growing area of corannulene-based nanographenes.In essence, corannulene presents a unique building block in the construction of functional materials. In this Account, we trace our own efforts in the field and point toward the challenges and future prospects of this area of research.

6.
Chemistry ; 26(66): 15135-15139, 2020 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-32935415

RESUMO

Monobromo-, tetrabromo-, and pentachloro-corannulene are subjected to nucleophilic substitution reactions with tolyl selenide and phenyl telluride-based nucleophiles generated in situ from the corresponding dichalcogenides. In the case of selenium nucleophile, the reaction provides moderate yields (52-77 %) of the targeted corannulene selenoethers. A subsequent oxidation of the selenium atoms proceeds smoothly to furnish corannulene selenones in 81-93 % yield. In the case of tellurides, only monosubstitution of the corannulene scaffold could be achieved albeit with concomitant oxidation of the tellerium atom. Unexpectedly, this monotelluroxide derivative of corannulene (RR'Te=O, R=Ph, R'=corannulene) is observed to form a linear coordination polymer chain in the crystalline state. In this chain, Te-O constitutes the polymer backbone around which the aromatic groups (R and R') arrange as polymer side-chains. The polymer crystal is stabilized through intramolecular π-π stacking interactions of the side-chains and intermolecular hydrogen and halogen bonding interactions with the solvent (chloroform) molecules. Interestingly, each diad of the polymer chain is racemic. Therefore, in terms of stereoregularity, the polymer chain can be described as syndiotactic.

7.
Chemistry ; 26(15): 3231-3235, 2020 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-31975463

RESUMO

It is shown in this work that high electron affinity can be combined with high solubility and practical accessibility in corannulene-based electron acceptors. The electron affinity originates from the presence of three different types of electron-withdrawing groups (imide, sulfone, and trifluoromethyl) on the aromatic scaffold. The imide substituent further hosts a long alkyl chain (C18 H37 ) to boast solubility in a wide range of organic solvents. The synthesis is modular and consists of three simple steps from a commonly available corannulene derivative with an overall isolated yield of 22-27 %.

8.
Angew Chem Int Ed Engl ; 59(48): 21620-21626, 2020 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-32770615

RESUMO

It is shown that corannulene-based strained π-surfaces can be obtained through the use of mechanochemical Suzuki and Scholl reactions. Besides being solvent-free, the mechanochemical synthesis is high-yielding, fast, and scalable. Therefore, gram-scale preparation can be carried out in a facile and sustainable manner. The synthesized nanographene structure carries positive (bowl-like) and negative (saddle-like) Gaussian curvatures and adopts an overall quasi-monkey saddle-type of geometry. In terms of properties, the non-planar surface exhibits a high electron affinity that was measured by cyclic voltammetry, with electrolysis and in situ UV/vis spectroscopy experiments indicating that the one-electron reduced state displays a long lifetime in solution. Overall, these results indicate the future potential of mechanochemistry in accessing synthetically challenging and functional curved π-systems.

9.
J Org Chem ; 83(7): 3529-3536, 2018 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-29518317

RESUMO

The first family of extended and fluorinated corannulenes is prepared through a highly efficient and modular synthetic strategy. In this strategy, corannulene aldehyde could be combined with the fluorine-carrying phosphonium ylides to furnish stilbene-like vinylene precursors. A photochemically induced oxidative cyclization process of these precursors gives rise to the fluorinated and curved polycyclic aromatic hydrocarbons. A UV-vis absorption study shows that aromatic extension results in a bathochromic shift of about 12 nm. Fluorination further shifts the absorption spectrum to the red region, and a maximum shift of about 22 nm is detected for a compound carrying two trifluoromethyl groups. A cyclic and square-wave voltammetry investigation reveals that the extension of the corannulene scaffold increases the reduction potential by 0.11 V. Placement of fluorine or trifluoromethyl groups further enhances the electron affinities. In this regard, the presence of one trifluoromethyl group equals the effect of three aromatic fluorine atoms. Molecules with two trifluoromethyl groups, meanwhile, exhibit the highest reduction potentials of -1.93 and -1.83 V. These values are 0.37 and 0.46 V higher than those of the parental corannulene and demonstrate the utility of the present design concept by efficiently accessing effective electron acceptors based on the buckybowl motif.

10.
J Am Chem Soc ; 139(8): 3089-3094, 2017 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-28221031

RESUMO

A new family of π-conjugated oligomers featuring a nonplanar polycyclic aromatic hydrocarbon, corannulene, and a planar aromatic unit, thiophene, is synthesized through an iterative metal-catalyzed coupling protocol. The two structural motifs are connected through an acetylene linkage. In the shorter oligomers, a thiophene unit is attached to one or two corannulenes. In the higher analogues, two, three, and four thiophene units are placed in an alternating fashion with three, four, and five corannulene units, respectively. Photophysical studies reveal extended π-effects that initially increase and then attenuate as a function of the oligomer length. Notably, longer oligomers are found to be highly active for nonlinear absorption and emission properties. The oligomer with three corannulene and two thiophene units exhibits a two-photon absorption cross section of 600 GM and two-photon-excited intense green luminescence. This work, therefore, introduces the concept of combining planar and nonplanar aromatic motifs in the design of π-conjugated discrete oligomers, establishes synthetic feasibility of such hybrid materials, reports on their photophysical properties that is anticipated to have significant implications for future research targets, and features the discovery that corannulene derivatives can exhibit excellent nonlinear optical activity when extended through π-bridges.

11.
Biomacromolecules ; 15(5): 1707-15, 2014 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-24754338

RESUMO

In this study, we systematically explore the influence of the lipophilic group on the siRNA transfection properties of the polycationic-based delivery vectors. For this, a novel and modular synthetic strategy was developed for the preparation of polymers carrying a cationic site and a lipophilic group at each polymer repeat unit. These bifunctional polymers could form a complex with siRNA and deliver it to human colon carcinoma cells (HT-29-luc). In general, transfection capability increased with an increase in the chain length of the lipophilic moiety. The best transfection agent, a polymer containing ammonium groups and pentyl side chains, exhibited lower toxicity and higher transfection efficiency than branched and linear polyethylenimines (PEI). Moreover, as opposed to PEI, the transfection efficiency of polymer/siRNA complexes remained unchanged in the presence of bafilomycin A1, a proton pump inhibitor, suggesting that the present system did not rely on the "proton sponge" effect for siRNA delivery.


Assuntos
Portadores de Fármacos/química , Polietilenoimina/química , RNA Interferente Pequeno/administração & dosagem , Transfecção/métodos , Portadores de Fármacos/administração & dosagem , Células HT29 , Humanos , Interações Hidrofóbicas e Hidrofílicas , Macrolídeos/farmacologia , Estrutura Molecular , Polietilenoimina/administração & dosagem , RNA Interferente Pequeno/química
12.
Soft Matter ; 10(31): 5755-62, 2014 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-24979238

RESUMO

Self-assembly of a binary mixture of poly(styrene)336-block-poly(4-vinyl pyridine)25 (PS336-b-P4VP25) and poly(ethylene glycol)113-block-poly(4-hydroxy styrene)25 (PEG113-b-P4HS25) is shown to give rise to a cylindrical morphology in thin films through pyridine/phenol-based hetero-complementary hydrogen bonding interactions between the P4VP and P4HS copolymer segments. Removal of the cylindrical phase (PEG-b-P4HS) allowed access to porous materials having a pore surface decorated with P4VP polymer blocks. These segments could be transformed into cationic polyelectrolytes through quaternization of the pyridine nitrogen atom. The resulting positively charged nanopore surface could recognize negatively charged gold nanoparticles through electrostatic interactions. This work, therefore, outlines the utility of the supramolecular AB/CD type of block copolymer towards preparation of ordered porous thin films carrying a chemically defined channel surface with a large number of reactive sites.

13.
Chemistry ; 19(39): 13199-206, 2013 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-23939633

RESUMO

Herein, we explore the synthesis of corannulene-based ribbon-shaped molecules through a repetitive Diels-Alder strategy. For this, appropriate corannulene-based dienes and dienophiles were identified and synthesized. These building blocks could be combined in a modular way to obtain the dimeric and trimeric segments of the hypothetical molecular ribbons. 1D and 2D NMR measurements, along with crystal-structure analyses, allowed the structures and geometries of the synthesized compounds to be determined.

14.
Angew Chem Int Ed Engl ; 52(30): 7786-90, 2013 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-23765590

RESUMO

A class of its own: A new class of fullerene C60 hosts--polymeric in nature--has been developed by careful design of the molecular structure of the polymer repeat unit and the mode of interaction between the repeat unit and C60 (see picture). As these hosts are synthesized by free-radical polymerization, polymer hosts with various chemical compositions and architectures can be constructed readily by appropriate design of the receptor monomer.

15.
ChemSusChem ; 16(20): e202301087, 2023 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-37581302

RESUMO

Corannulene, a curved polycyclic aromatic hydrocarbon, is prepared in a multigram scale through mechanochemical synthesis. Initially, a mixer mill approach is examined and found to be suitable for a gram scale synthesis. For larger scales, planetary mills are used. For instance, 15 g of corannulene could be obtained in a single milling cycle with an isolated yield of 90 %. The yields are lower when the jar rotation rate is lower or higher than 400 revolutions per minute (rpm). Cumulatively, 98 g of corannulene is produced through the ball milling-based grinding techniques. These results indicate the future potential of mechanochemistry in the rational chemical synthesis of highly curved nanocarbons such as fullerenes and carbon nanotubes.

16.
Nat Commun ; 14(1): 803, 2023 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-36781875

RESUMO

While the synthesis of nanographenes has advanced greatly in the past few years, development of their atomically precise functionalization strategies remains rare. The ability to modify the carbon scaffold translates to controlling, adjusting, and adapting molecular properties. Towards this end, here, we show that mechanochemistry is capable of transforming graphitization precursors directly into chlorinated curved nanographenes through a Scholl reaction. The halogenation occurs in a regioselective, high-yielding, and general manner. Density Functional Theory (DFT) calculations suggest that graphitization activates specific edge-positions for chlorination. The chlorine atoms allow for precise chemical modification of the nanographenes through a Suzuki or a nucleophilic aromatic substitution reaction. The edge modification enables modulation of material properties. Among the molecules prepared, corannulene-coronene hybrids and laterally fully π-extended helicenes, heptabenzo[5]superhelicenes, are particularly noteworthy.

17.
J Am Chem Soc ; 134(41): 17291-7, 2012 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-23025462

RESUMO

Poly(ß-hydroxyl amine)s are prepared from readily available small molecular building blocks at ambient conditions. These macromolecules can be transformed into main-chain cationic polymers upon quaternization of the backbone amine units. The modular and mild nature of the synthesis allows for incorporation of multiple (2-4) chemically distinct reactive sites in the polymer chain. Modifications of the reactive sites afford multifunctional polymers with tunable properties. The orthogonal nature of the involved chemistries sets the synthetic pathway free from any functional group protection/deprotection requirements. This feature also allows for alteration of the modification sequence.


Assuntos
Poliaminas/síntese química , Cátions/síntese química , Cátions/química , Química Click , Estrutura Molecular , Poliaminas/química
18.
J Org Chem ; 77(24): 11014-26, 2012 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-23171240

RESUMO

Electrochemically active corannulene derivatives with various numbers of electron-donating 4-(N,N-dimethylamino)phenylethynyl (1-4) or electron-withdrawing cyanobutadienyl peripheral substitutents (5-8) were prepared. The latter derivatives resulted from formal [2 + 2] cycloaddition of cyanoolefins to 1-4 followed by retro-electrocyclization. Conformational properties were examined by variable-temperature NMR and X-ray diffraction and opto-electronic properties by electronic absorption/emission spectra and electrochemical measurements; these analyses were corroborated by dispersion-corrected density functional calculations at the level of B97-D/def2-TZVPP. In CH(2)Cl(2), 1-4 exhibit intramolecular charge-transfer (ICT) absorptions at 350-550 nm and green (λ(em) ~ 540 nm) or orange (600 nm) fluorescence with high quantum yields (56-98%) and are more readily reduced than corannulene by up to 490 mV. The variation of optical gap and redox potentials of 1-4 does not correlate with the number of substituents. Cyanobutadienyl corannulenes 5-8 show red-shifted ICT absorptions with end-absorptions approaching 800 nm. Intersubstituent interactions lead to distortions of the corannulene core and lower the molecular symmetry. NMR, X-ray, and computational studies on 5 and 8 with one cyanobutadienyl substituent suggested the formation of intermolecular corannulene dimers. Bowl-inversion barriers around ΔG(‡) = 10-11 kcal/mol were determined for these two molecules.

19.
Chem Asian J ; 17(14): e202200602, 2022 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-35785474

RESUMO

This special collection of Chemistry - An Asian Journal features contributions made by female scientists working in the field of chemistry. In her editorial, Mihaiela C. Stuparu briefly describes the background that led to the conception of this special collection. The table of contents graphic was created by Lim Pei Xi.


Assuntos
Química , Feminino , Humanos
20.
Chimia (Aarau) ; 65(10): 799-801, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22054134

RESUMO

In an attempt to introduce corannulene chemistry to macromolecular science, my research program is dedicated to synthetic strategies leading to corannulene-based polymers with interesting architectures and properties. In this brief account, I will discuss the synthesis of a variety of corannulene-based building blocks (monomers) and their utility in the preparation of a wide range of corannulene-rich macromolecular structures.


Assuntos
Química/métodos , Substâncias Macromoleculares/química , Hidrocarbonetos Policíclicos Aromáticos/química , Polímeros/química , Dendrímeros , Luz , Modelos Químicos , Conformação Molecular , Estrutura Molecular , Energia Solar
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