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There is resurgent interest in atomically precise nanographene radical ions composed of fused hexagons. Two monoradical anions can readily form a doubly negatively charged π-dimer, but to our knowledge, no triply negatively charged π-dimer species have been isolated till now. Herein we report the largest open-shell grapheneic bilayer and also the first example of triply negatively charged radical π-dimer. Upon three-electron reduction, bilayer nanographene fragment molecule (C96H24Ar6)2 (Ar = 2,6-dimethylphenyl) (12) was transformed to a triply negatively charged species 123•-, which has been characterized by single-crystal X-ray diffraction, EPR spectroscopy and SQUID measurements. 123•- features a 96-center-3-electron (96c/3e) pancake bond with a doublet ground state, which can be thermally excited to a quartet state. It is the largest open-shell nanographene bilayer species till now constructed with 34 π-fused rings with 96 conjugated sp2 carbon atoms. Spin frustration is observed with the frustration parameter f = |θcw|/TN31.8 at low temperatures in 123•-, which indicates graphene upon reduction doping may behave as quantum spin liquids.

As a fundamental chemical property, aromaticity guides the synthesis of novel structures and materials. Replacing the carbon moieties of aromatic hydrocarbons with transition metal fragments is a promising strategy to synthesize intriguing organometallic counterparts with a similar aromaticity to their organic parents. However, since antiaromaticity will endow compound instability, it is a great challenge to obtain an antiaromatic organometallic counterpart based on such transition metal replacement in aromatic hydrocarbons. Here, we report an efficient aromaticity transformation on aromatic naphthalene through the bridgehead replacement of an osmium fragment, leading to the unprecedented synthesis of metal-bridgehead naphthalene featuring a highly twisted structure as confirmed by X-ray crystallography characterization. Such a twisted conformation works together with its phosphonium substituents to release the antiaromaticity in the planar conformation of the metal-bridgehead naphthalene. Our findings prove the bridgehead involvement of transition metals in unexpected aromaticity modifications and open an avenue for novel metal-bridgehead complexes.

Nanographenes are inclined to assemble into stacked columnar structures that are stabilized by π-π interactions, whereas other supramolecular structures of nanographenes, such as prisms and cages, are rarely investigated. Herein, a diazananographene was synthesized, and then assembled with a coordination unit, thereby producing a triangular metallaprism. After adding C

The bottom-up approach through on-surface synthesis of porous graphene nanoribbons (GNRs) presents a controllable manner for implanting periodic nanostructures to tune the electronic properties of GNRs in addition to bandgap engineering by width and edge configurations. However, owing to the existing steric hindrance in small pores like divacancies, it is still difficult to embed periodic divacancies with a nonplanar configuration into GNRs. Here, we demonstrate the on-surface synthesis of atomically precise eight-carbon-wide armchair GNRs embedded with periodic divacancies (DV8-aGNRs) by utilizing the monatomic step edges on the Au(111) surface. From a single molecular precursor correspondingly following a

Here, we report a facile method to synthesize a series of macrocycles with different conformations. The planar macrocycle dimer (1), twisted macrocycle trimer (2) and "figure-eight" tetramer (3) are clearly elucidated by X-ray single-crystal analysis, in which the electron-rich phenanthrene units offer the possibility of supramolecular assembly. As expected, in the solid state, 1 and 3 assemble into a columnar stack and an interlocking dimer, respectively, via π-π interactions between the phenanthrene units. Compared to the rigid conformation of dimer 1, the structure of tetramer 3 is more flexible due to its enlarged ring size. 3 can deform from a figure-eight into a boat-shaped geometry to host a planar electron-deficient guest using its electron-rich phenanthrene units. When assembled with spherical electron-deficient C60 , interestingly, 3 further undergoes a conformational transformation from a figure-eight to a belt shape in order to host C60 . These supramolecular assembly behaviors of 3 demonstrate that it is an adaptable macrocyclic host for both planar molecules and fullerenes.

Although heptagons are widely found in graphenic materials, the precise synthesis of nanocarbons containing heptagons remains a challenge, especially for the nanocarbons containing multiple-heptagons. Herein, we show that photo-induced radical cyclization (PIRC) can be used to synthesize multi-heptagon-embedded nanocarbons. Notably, a nanographene containing six heptagons (1) was obtained via a six-fold cascade PIRC reaction. The structure of 1 was clearly validated and showed a Monkey-saddle-shaped conformation. Experimental bond analysis and theoretical calculations indicated that the heptagons in 1 were non-aromatic, whereas the peripheral rings were highly aromatic. Compared to planar nanographene with the same number of π electrons, 1 had a similar optical gap due to a compromise between the decreased conjugation in the wrapped structure and enhanced electronic delocalization at the rim. Electrochemical studies showed that 1 had low-lying oxidation potentials, which was attributed to the nitrogen-doping.

The radial conjugated π-system of cycloparaphenylenes (CPPs) makes them intriguing fluorophores and unique supramolecular hosts. However, the bright photoluminescence (PL) of CPPs was limited to the blue light and the supramolecular assembly behavior of large CPPs was rarely investigated. Here we present the synthesis of tetra-benzothiadiazole-based [12]cycloparaphenylene (TB[12]CPP), which exhibits a lime to orange PL with an excellent quantum yield up to 82 % in solution. The PL quantum yield of TB[12]CPP can be further improved to 98 % in polymer matrix. Benefiting from its enlarged size, TB[12]CPP can accommodate a fullerene derivative or concave-convex complexes of fullerene and buckybowl through the combined π-π and C-H⋅⋅⋅π interactions. The latter demonstrates the first case of a ternary supramolecule of CPPs.

All-inorganic and earth-abundant bi-/trimetallic hydr(oxy)oxides are widely used as oxygen evolution electrocatalysts owing to their remarkable performance. However, their atomically precise struct ...

Bowl inversion is a unique property of buckybowls. The polarity and assembly configuration of buckybowls are reversed after bowl inversion. So far, this unique phenomenon has been studied in solution and on surface, but not in solid state due to spatial constraint. Now a series of exo-type supramolecular assemblies of trithiasumanene and nanographene are investigated. Tuning the electron density of the nanogaphene component was found to directly affect the binding constant of the complex. Reversible bowl inversion in the solid state was then successfully achieved by subjecting the trithiasumanene-nanographene assembly with the weakest binding strength to repeated heating-cooling cycles, which was unambiguously observed by single crystal X-ray diffraction.

Tumor microenvironment-induced ultrasmall nanodrug generation (TMIUSNG) is an unprecedented approach to overcome the drug penetration barriers across complex biological systems, poor circulation stability and limited drug loading efficiency (DLE). Herein, a novel strategy was designed to synthesize metal-organic nanodrug complexes (MONCs) through supramolecular coassembly of photosensitizer sinoporphyrin sodium, chemotherapeutic drug doxorubicin and ferric ions. Compared with the free photosensitizer, MONCs produced 3-fold more reactive oxygen species (ROS) through the energy transfer-mediated fluorescence quenching. Remarkably, the self-delivering supramolecular MONCs with high DLE acted as a potent ultrasmall-nanodrug generator in response to the mild acidic tumor microenvironment to release ultrasmall nanodrugs (5-10 nm in diameter) from larger parental nanoparticles (140 nm in diameter), which in turn enhanced the intratumor permeability and therapeutic efficacy. The key mechanism of MONC synthesis was proposed, and we, for the first time, validated the generation of supramolecular scaffold intermediates between MONCs' assembly/disassembly states, as well as their involvement in multidrug ligands interactions. This proof-of-concept TMIUSNG strategy provides a foundation for the rational design of analogous carrier-free nanotheranostics through the combination of multiple therapeutic agents and metal ions with imaging functions.

By artificial mimic of the natural [FeFe]-hydrogenases, a series of polyoxometalate-based high-nuclear Ni clusters containing a varying number of {Ni 4 O 4 } cubane cores, K 1.5 Na 26.5 [{Ni 4 (OH) 3 (PO 4 )} 4 ( A- PW 9 O 34 ) 4 ]·62H 2 O ( 1 ), Na 28 [{Ni 4 (OH) 3 (PO 4 )} 4 ( A- PW 9 O 34 ) 2 ( B- PW 9 O 34 ) 2 ]·102H 2 O ( 2 ), and Na 28 [{Ni 4 (OH) 3 (VO 4 )} 4 ( B- PW 9 O 34 ) 4 ]·74H 2 O ( 3 ), were synthesized and systematically characterized. Compounds 1 − 3 contain {Ni 16 (XO 4 ) 4 (OH) 12 } (X = P, V) core encapsulated by the trivacant A- / B- {PW 9 O 34 } ligands. Compounds 1 − 3 as homogeneous catalysts for visible-light-driven H 2 evolution indicate that they not only show high photocatalytic performance (High TON of 578.8, 679.1, and 931.1 for 1 − 3 were achieved, respectively), but also their catalytic performance was improved with the increasing number of {Ni 4 O 4 } cubanes. Multiple stability experiments confirm that compounds 1 − 3 maintain their structure intact under the photocatalytic conditions. The above research provides a platform for mimicking the structures of natural hydrogenases to further explore more efficient and inexpensive H 2 evolution catalysts.

The oxygen evolution reaction is a crucial step in water electrolysis to develop clean and renewable energy. Although noble metal-based catalysts have demonstrated high activity for the oxygen evolution reaction, their application is limited by their high cost and low availability. Here we report the use of a molecule-to-cluster strategy for preparing ultrasmall trimetallic clusters by using the polyoxometalate molecule as a precursor. Ultrafine (0.8 nm) transition-metal clusters with controllable chemical composition are obtained. The transition-metal clusters enable highly efficient oxygen evolution through water electrolysis in alkaline media, manifested by an overpotential of 192 mV at 10 mA cm–2, a low Tafel slope of 36 mV dec–1, and long-term stability for 30 h of electrolysis. We note, however, that besides the excellent performance as an oxygen evolution catalyst, our molecule-to-cluster strategy provides a means to achieve well-defined transition-metal clusters in the subnanometer regime, which p...

Buckybowls are fascinating components of supramolecular assemblies owing to their unique bowl-shaped π-surfaces. Herein we present a protocol for the functionalization of a sulfur-doped buckybowl, trithiasumanene, via a brominated intermediate, from which thiolated trithiasumanenes were derived. The curved surface and electron-donating properties of thiolated trithiasumanenes promote their ready assembly with fullerenes to form concave-convex complexes. The supramolecular assembly behavior in solution was investigated by NMR analysis. The structures of supramolecular complexes were unambiguously characterized by crystallography. The crystals of the concave-convex complexes showed high thermal stability and photoconductivity.

So far the entrapped metals for the isolated endohedral metallofullerenes (EMFs) are primarily limited to rare earth metals, whereas except group-IVB metals, whether it is possible to entrap other d-block transition metals remains unclear. Herein we report the successful entrapment of the group-VB transition metal vanadium(V) into fullerene cage, affording the heretofore unknown V-containing EMFs. Two novel V-containing EMFs--V(x)Sc(3-x)N@C80 (x = 1, 2)--were isolated, and their molecular structures were unambiguously determined by X-ray crystallography to be I(h)(7)-C80 cage entrapping the planar VSc2N/V2ScN clusters. V(x)Sc(3-x)N@I(h)(7)-C80 (x = 1, 2) were further characterized by UV-vis-NIR and ESR spectroscopies and electrochemistry, revealing that the electronic and magnetic properties of V(x)Sc(3-x)N@I(h)(7)-C80 (x = 1, 2) are tunable upon varying the number of entrapped V atoms (i.e., x value). The molecular structures and electronic properties of V(x)Sc(3-x)N@I(h)(7)-C80 (x = 1, 2) were further compared with those of the reported analogous EMFs based on lanthanide metals and the adjacent group-IVB transition metal Ti, revealing the peculiarity of the group-VB transition metal V-based EMFs.

The chemical nature of the edge periphery essentially determines the physical properties of graphene. As a molecular-level model system, large polycyclic aromatic hydrocarbons, that is, so-called nanographenes, can be chemically modified through either edge functionalization or doping with heteroatoms. Although the synthetic methods for edge substitution are well-developed, incorporation with heteroatoms by the bay annulation of large PAHs remains an enormous challenge. In this study, we present a feasible peripheral sulfur annulation of hexa-peri-hexabenzocoronene (HBC) by thiolation of perchlorinated HBC. The tri-sulfur-annulated HBC and di-sulfur-annulated HBC decorated with phenylthio groups were obtained and characterized by X-ray diffraction, revealing their distinct sulfur-annulated peripheral structure. Associated with theoretical calculations, we propose that the regioselective sulfur annulation results from the minimization of strain in the aromatic backbone. We further demonstrate the structure-correlated property modulation by sulfur annulation, manifested by a decrease in band gap and tunable redox activity.

In search of functional molecular materials and the study of their formation mechanism, we report the elucidation of a hierarchical step-by-step formation from monomer (Mn) to heptamer (Mn7) to nonadecamer (Mn19) satisfying the relation 1 + Σn6n, where n is the ring number of the Brucite structure using high-resolution electrospray ionization mass spectrometry (HRESI-MS). Three intermediate clusters, Mn10, Mn12, and Mn14, were identified. Furthermore, the Mn19 disc remains intact when dissolved in acetonitrile with a well-resolved general formula of [Mn19(L)x(OH)y(N3)36-x-y](2+) (x = 18, 17, 16; y = 8, 7, 6; HL = 1-(hydroxymethyl)-3,5-dimethylpyrazole) indicating progressive exchange of N3(-) for OH(-). The high symmetry (R-3) Mn19 crystal structure consists of a well-ordered discotic motif where the peripheral organic ligands form a double calix housing the anions and solvent molecules. From the formula and valence bond sums, the charge state is mixed-valent, [Mn(II)15Mn(III)4]. Its magnetic properties and electrochemistry have been studied. It behaves as a ferrimagnet below 40 K and has a coercive field of 2.7 kOe at 1.8 K, which can be possible by either weak exchange between clusters through the anions and solvents or through dipolar interaction through space as confirmed by the lack of ordering in frozen CH3CN. The moment of nearly 50 NμB suggests Mn(II)-Mn(II) and Mn(III)-Mn(III) are ferromagnetically coupled while Mn(II)-Mn(III) is antiferromagnetic which is likely if the Mn(III) are centrally placed in the cluster. This compound displays the rare occurrence of magnetic ordering from nonconnected high-spin molecules.

The catalytic performances of bifunctional vanadium oxide supported on Hβ zeolite with redox and acid properties were investigated for dimethyl ether (DME) direct oxidation to polyoxymethylene dimethyl ethers (DMMx) (x=1-2). The best catalytic performance was obtained over 15%V2O5/Hβ. The catalysts were characterized by XRD, BET, NH3-TPD, H2-TPR, XPS and FT-IR in order to provide the further insight in the relationship of structure and activity. When the loading content of vanadium oxide was 15%, the presence of oxide species was dominantly the polymeric vanadia. The addition of vanadium oxide to the H-beta zeolite not only provided redox sites, but also changed the acid strength and distribution of H-beta zeolite as confirmed by NH3-TPD measurement, and the positive correlation was found between the DMMx selectivity and the ratio of weak and strong acid sites. The introduction of vanadium oxide with appropriate amount to the H-beta zeolite promoted the balance between the acid sites and redox sites, which was very vital for obtaining high DMMx selectivity.

Here we report hexathienocoronenes (HTCs), fully thiophene-annelated coronenes in which six double bonds in the periphery are thieno-fused. The derivatives tetrasubstituted with hexyl and dodecyl chains show a phase formation that strongly depends on the chain length. HTCs are remarkably stronger donors than the known thiophene-annelated coronenes but do not readily assemble into well-ordered films when deposited from the vapor phase. Thus, thin-film transistors fabricated by vacuum deposition have only modest field-effect mobilities of 0.002 cm(2) V(-1) s(-1).

C(78) is one of the most widely investigated higher fullerenes. Among its huge isomer family, only one non-IPR (IPR = isolated pentagon ring) cage, the C(2)-symmetric (#22010)C(78), was previously stabilized by endohedral derivatization. Here we report a new C(1)-symmetric non-IPR hollow isomer, (#23863)C(78), which was captured as (#23863)C(78)Cl(8) and then subjected to a regioselective substitution reaction with benzyl hydroperoxide to form (#23863)C(78)(OOCH(2)C(6)H(5))Cl(7). The structural connectivity of (#23863)C(78), which contains a pair of fused pentagons, was confirmed by single-crystal X-ray diffraction analysis of the (#23863)C(78)(OOCH(2)C(6)H(5))Cl(7) molecule, which shares the same fullerene core with (#23863)C(78)Cl(8); support for the structure is provided by comparable IR measurements and computation. Theoretical studies suggest that the differences in C-Cl bond length, intermediate stability, and steric effects of the involved molecules account for the chemical regioselectivity of the substitution reaction.

A general class of C3 -symmetric Ag9 clusters, [Ag9 S(tBuC6 H4 S)6 (dpph)3 (CF3 SO3 )] (1), [Ag9 (tBuC6 H4 S)6 (dpph)3 (CF3 SO3 )2 ]⋅CF3 SO3 (2), [Ag9 (tBuC6 H4 S)6 (dpph)3 (NO3 )2 ] ⋅NO3 (3), and [Ag9 (tBuC6 H4 S)7 (dpph)3 (Mo2 O7 )0.5 ]2 ⋅2 CF3 COO (4) (dpph=1,6-bis(diphenylphosphino)hexane), with a twisted trigonal-prism geometry was isolated by the reaction of polymeric {(HNEt3 )2 [Ag10 (tBuC6 H4 S)12 ]}n , 1,6-bis(diphenylphosphino)hexane, and various silver salts under solvothermal conditions. The structures consist of discrete clusters constructed from a girdling Ag9 twisted trigonal prism with the top and bottom trigonal faces capped by diverse anions (i.e., S(2-) and CF3 SO3 (-) for compound 1, 2×CF3 SO3 (-) for compound 2, 2×NO3 (-) for compound 3, and tBuC6 H4 S(-) and Mo2 O7 (2-) for compound 4). This trigonal prism is bisected by another shrunken Ag3 trigon at its waist position. Interestingly, two inversion-related Ag9 trigonal-prismatic clusters are dimerized by the Mo2 O7 (2-) ion in compound 4. The twist is amplified by the bulkier thiolate, which also introduces high steric-hindrance for the capping ligand, that is, the longer dpph ligand. Four more silver-sulfur clusters (namely, compounds 5-8) with their nuclearity ranging from 6-10 were solely characterized by single-crystal X-ray diffraction to verify the above-described synergetic effect of mixed ligands in the construction of Ag9 twisted trigonal prisms. Surprisingly, only cluster 1 emits yellow luminescence at λ=584 nm at room temperature, which may be attributed to a charge transfer from the S 3p orbital to the Ag 5s orbital, or mixed with metal-centered (MC) d(10) →d(9) s(1) transitions. Upon cooling from 300 to 80 K, the emission intensity was enhanced along with a hypsochromic shift. The good linear relationship between the maximum emission intensity and the temperature for compound 1 in the range of 180-300 K indicates that this is a promising molecular luminescent thermometer. Furthermore, cyclic voltammetric studies indicated that the diffusion- and surface-controlled redox processes were determined for compounds 1 and 3 as well as compound 4, respectively.

The long-sought small-bandgap endohedral fullerene Sc3N@C82 with low kinetic stability has been successfully synthesized and isolated for the first time, for which the molecular structure has been unambiguously determined as Sc3N@C82-C2v(39718) by single crystal X-ray diffraction. The C82-C2v(39718) (or labeled as C82-C2v(9) according to the conventional numbering of the isolated pentagon rule (IPR) isomers based on the Fowler-Monolopoulos spiral algorithm) isomeric cage of Sc3N@C82 agrees well with its most stable isomer previously predicted by DFT computations and is dramatically different to those of the reported counterparts M3N@C82-Cs(39663) (M = Gd, Y) based on a non-IPR C82 isomer, revealing the strong dependence of the cage isomeric structure on the size of the encaged metal for C82-based metal nitride clusterfullerenes (NCFs).

Graphene nanoribbons (GNRs), defined as nanometer-wide strips of graphene, have attracted increasing attention as promising candidates for next-generation semiconductors. Here, we demonstrate a bottom-up strategy toward novel low band gap GNRs (E-g = 1.70 eV) with a well-defined cove-type periphery both in solution and on a solid substrate surface with chrysene as the key monomer. Corresponding cyclized chrysene-based oligornerS consisting of the dimer and tetramer are obtained via an Ullmann Coupling followed by oxidative intramolecular cyclodehydrogenation in solution, and much higher GNR homologues via on-surface synthesis. These oligomers adopt nonplanar structures due to the isteric repulsion between the two C-H bonds at the inner cove position. Characterizations by single crystal X-ray analysis, UV-vis absorption spectroscopy, NMR spectroscopy, and scanning tunneling microscopy (STM) are described. The interpretation is assisted by density functional theory (DFT) calculations.

通讯作者地址: Xie, SY (通讯作者),Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 2. Xiamen Univ, Dept Chem, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China 电子邮件地址: syxie@xmu.edu.cn

A long-sought empty non-IPR fullerene, (#11188)C72, which is more stable than the sole IPR isomer in the fullerene[72] family, has been retrieved and crystallographically characterized as (#11188)C72Cl4. Mass spectrometric data support the facile dechlorination of (#11188)C72Cl4 and, in turn, the possible stability of pristine (#11188)C72.

A smaller fullerene C56 (#913) is stabilized, isolated, and crystallographically characterized as C56Cl10. The geometric parameters of C56Cl10 imply the otherwise unstable cage of C56 can be stabilized by chlorination through releasing its surface strains and maintaining fragmental aromaticity. An unexpected C Cl...ClC short contact, as well as the linear alignment with pearl-necklace-shaped, is revealed in C56Cl10 crystal.

Diindeno-fused bischrysene, a new diindeno-based polycyclic hydrocarbon (PH), was synthesized and characterized. It was elucidated in detailed experimental and theoretical studies that this cyclopenta-fused PH possesses an open-shell singlet biradical structure in the ground state and exhibits high stability under ambient conditions (t1/2=39 days). The crystal structure unambiguously shows a novel saddle-shaped π-conjugated carbon skeleton due to the steric hindrance of the central cove-edged bischrysene unit. UV/Vis spectral measurements revealed that the title molecule has a very narrow optical energy gap of 0.92 eV, which is consistent with the electrochemical analysis and further supported by density functional theory (DFT) calculations.