Supramolecular Hybrid Research Articles

Hydrothermal synthesis and characterization of a novel supramolecular hybrid based on Keggin and Cu(I) complex

A novel inorganic–organic hybrid molecule, [Cu(4,4′bipyH)3(4,4bipy)][HPW12O40]2.12H2O (1), has been hydrothermally synthesized and characterized by IR spectra, TG and single crystal X-ray diffraction analyses. Structural analysis reveals that the novel compound 1 composed of two Kegging polyoxoanion connected with Cu complex fragment forming a big molecule that extends in 3D via hydrogen bonding.

ChemInform Abstract: Gold Nanoparticles Functionalized with Supramolecular Macrocycles

AbstractReview: 67 refs.

Arginine-responsive terbium luminescent hybrid sensors triggered by two crown ether carboxylic acids

Crown ether carboxylic acids constitute main building blocks for the synthesis of terbium containing covalent cross-linked luminescent materials. Both the complexes and the hybrid nanomaterials could exhibit remarkable green emissions in pure water. More importantly, they were found to have a profound effect on the luminescence responses to arginine compared with glutamic acid, histidine, tryptophan, threonine, tyrosine and phenylalanine in aqueous environment. The present study provided the possibility of using a host–guest mechanism as a way of signal transduction based on lanthanide supramolecular hybrid materials.

Thermo-Responsive Supramolecular Hybrid Hydrogels Formed by Graphene Oxide-Grafted-Poly(Ethylene Glycol) and α-Cyclodextrin

Poly(ethylene glycol) methyl ether-grafted-graphene oxide (GO) was synthesized by a coupling reaction and formed inclusion complexes (ICs) after selective threading of the mPEG segments of the GO-mPEG through the cavities of α-cyclodextrins (α-CDs) units. The polypseudorotaxane structures of the as-obtained hydrogels were confirmed by X-ray diffraction, TGA, DSC, and SEM. The complexation of the mPEG segments with α-CDs and the hydrogen-bond interaction between CDs resulted in the formation of supramolecular hybrid hydrogels with a strong network. The resultant hybrid hydrogels were found to be thermo-responsive, and could be applied as a promising drug delivery system.

Gold nanoparticles functionalized with supramolecular macrocycles

Gold nanoparticles (AuNPs) functionalized with supramolecular macrocycles are versatile and diverse hybrid nanomaterials, which combine and enhance the characteristics of the two components. In this mini-review, we summarize the recent research progress on the synthesis and assembly of AuNPs functionalized with different supramolecular macrocyclic compounds, i.e., crown ethers, cyclophanes, cyclodextrins (CDs), cucurbit[n]urils (CB[n]), calix[n]arenes, and pillar[n]arenes (P[n]A). Meanwhile, applications of these supramolecular hybrid nanomaterials in the fields of sensors, biomedicine and plasmonic devices are also presented.

A perspective on carbon materials for future energy application

Nanocarbon materials play a critical role in the development of new or improved technologies and devices for sustainable production and use of renewable energy. This perspective paper defines some of the trends and outlooks in this exciting area, with the effort of evidencing some of the possibilities offered from the growing level of knowledge, as testified from the exponentially rising number of publications, and putting bases for a more rational design of these nanomaterials. The basic members of the new carbon family are fullerene, graphene, and carbon nanotube. Derived from them are carbon quantum dots, nanohorn, nanofiber, nano ribbon, nanocapsulate, nanocage and other nanomorphologies. Second generation nanocarbons are those which have been modified by surface functionalization or doping with heteroatoms to create specific tailored properties. The third generation of nanocarbons is the nanoarchitectured supramolecular hybrids or composites of the first and second generation nanocarbons, or with organic or inorganic species. The advantages of the new carbon materials, relating to the field of sustainable energy, are discussed, evidencing the unique properties that they offer for developing next generation solar devices and energy storage solutions.

Supramolecular hybrid assemblies based on gold nanoparticles, amphiphilic cyclodextrin and porphyrins with combined phototherapeutic action

Gold nanoparticles (AuNPs), amphiphilic cyclodextrin (SC6NH2) and anionic porphyrin (TPPS4) spontaneously self-assemble in aqueous basic solution forming nanostructures with controlled size and shape. Spectroscopic techniques such UV-Vis, fluorescence emission and Dynamic Light Scattering (DLS) demonstrate that AuNPs are covered by SC6NH2, and TPPS4 is strongly entrapped within, forming assemblies with size of 4 and 50 nm. Scanning Near-Field Optical Microscopy (SNOM) and Scanning Near-Field Optical Luminescence (SNOL) assess the presence of luminescent vescicular structures incorporating porphyrin with dimensions of about 150 nm. Transmission electron microscopy (TEM) indicates AuNPs with sizes of 20–30 nm can be located inside the largest cyclodextrin/porphyrin aggregates (≅150 nm) or interact externally with the smallest cyclodextrin/porphyrin vesicles (≅ 40 nm). The generation of an appreciable quantum yield of singlet oxygen (ΦΔ = 0.25) guarantees the photodynamic action excluding mostly strong interactions between gold and porphyrin. These hybrid systems are fairly stable at physiological conditions (pH = 7.4) and can be taken up by HeLa cancer cells which, upon treatment, show co-localization of gold and porphyrins in the cytoplasm. After intracellular delivery, these assemblies induce low dark toxicity and a combined photothermal–photodynamic effect upon proper irradiation, showing promising properties as dual-action phototherapeutics.

Three unprecedent polycational templated cuprous thiocyanate networks: synthesis, structure, and properties

Inspired by the lack of supramolecular hybrids induced by the multivalent interactions, we conducted three integrations of trication or tetracation with thiocyanate via strict templated self-assembly. These compounds represent the first type of 2–3 dimensional multi-threading polypseudorotaxanes based on Cu6(SCN)6 macrocycles.

Photofunctional Hybrid Nanocarbon Materials

Zero-, one-, and two-dimensional nanostructured carbon allotropes, i.e., fullerenes, single-walled carbon nanotubes (SWNTs), and graphenes, in combination with electron-donating conjugated molecules are promising building blocks for artificial photosynthesis and solar energy conversion. This feature article focuses on the fundamental aspects of covalently linked composites of porphyrins with fullerenes, SWNTs, and graphenes. The linkage structures between the porphyrin and nanocarbons have been found to exert a substantial impact on their interaction between the components in the ground and excited states. We also highlight recent developments of supramolecular nanocarbon hybrid materials of fullerenes and SWNTs, where SWNTs are utilized as scaffolds or wires of self-assembled fullerenes for photoelectrochemical devices and organic photovoltaics.

A new heterometallic hybrid based on polymeric iodoplumbate and lanthanide metal-carboxylic coordination polycation

A 3-D supramolecular hybrid {[La(EPC)3(H2O)3]2(Pb6I18)}n (EPC+=N-ethyl-pyridium-4-carboxylate) (1) has been structurally determined, which assume significance for its incorporating lanthanide metal-carboxylic coordination polycation into polymeric iodoplumbate to get heterometallics. 1 consists of 1-D (Pb6I18)n6n- zigzag-like anion chains with lanthanide metalcarboxylic [La(EPC)3(H2O)3]n3n+ polycations, which arrange in a criss-cross configuration. C–H⋯I and C–H⋯O hydrogen bonds among inorganic anions and polycations contribute to the formation of a 3-D supramolecular framework. Moreover, the framework displays an absorption edge at 2.46eV which is comparable to PbI2’s absorption edge.

Application of Supramolecular Bidentate Hybrid Ligands in Asymmetric Hydroformylation

In this study we report a novel class of supramolecular bidentate hybrid ligands in which the two inequivalent phosphorus units and pyridine moieties are covalently attached to a chiral scaffold and the supramolecular interactions are used as a second handle to control the coordination sphere around the transition-metal centre. The coordination chemistry of these ligands was investigated under hydroformylation conditions by high-pressure NMR and IR spectroscopy, revealing the formation of a single active species in which the phosphane ligand is in the axial position and the phosphoramidite adopts the equatorial position. These ligands were applied in the asymmetric Rh-catalysed hydroformylation of styrene and para-substituted analogues. In these hydroformylation reactions, modification of the electronic and steric properties of the zinc(II)-templates appear to have a significant influence on the activity and selectivity of the catalysis. In particular, zinc(II)-templates bearing more electron-withdrawing substituents led to an increase in enantioselectivity.

Supramolecular Hybrid Bidentate Ligands in Asymmetric Hydrogenation

AbstractIn this study we introduce a novel class of supramolecular bidentate hybrid ligands and their application in the rhodium‐catalysed asymmetric hydrogenation of prochiral olefins. A new supramolecular strategy is reported in which the two nonequivalent phosphorus atoms are linked covalently to a chiral scaffold, and the supramolecular interactions are used to control the second coordination sphere of the transition‐metal catalyst. The supramolecular assembly is formed in situ by selective interaction between the nitrogen‐donor atoms and the zinc(II) template, which is essential for obtaining high activity and selectivity. The investigations of the different zinc(II) and ruthenium(II) templates on the reaction parameters revealed a dependence of the activity and selectivity on the association constant between the supramolecular template and the pyridyl ligands. The scope of the supramolecular assemblies was explored in the Rh‐catalysed asymmetric hydrogenation of α‐dehydroamino acid esters and Roche ester derivatives. High activities and good to excellent enantioselectivities up to 99 % ee were obtained with the supramolecular ligands. Application of the supramolecular strategy on the basis of variations of the steric and electronic properties of zinc(II) templates demonstrate that these changes can influence key reaction parameters such as activity and selectivity.

A POSS‐Based Supramolecular Amphiphile and Its Hierarchical Self‐Assembly Behaviors

A polyhedral oligomeric silsesquioxane (POSS)-based supramolecular amphiphile is prepared from the host-guest inclusion complexation between a mono adamantane-functionalized POSS (AD-POSS) and a β-cyclodextrin oligomer (P(β-CD)). Assisted by the interface of H(2)O/toluene, the obtained supramolecular hybrids self-assemble into stable hollow nanospheres with thick walls. These hollow nanospheres aggregate together into a sphere layer through a spin coating technique, which then further transforms into a thin porous film containing nanometer-scale holes. The hollow nanospheres have a low cytotoxicity. The in vitro cell culture indicates the nanoporous films promote adhesion and proliferation of cells. The self-assembly morphologies and structures have been carefully characterized by SEM, TEM, AFM, DLS, XPS and water-contact angle measurements, and the self-assembly mechanism has also been discussed.

Three new organic–inorganic hybrids based on Keggin ions and aminopyridine: Crystal structure and catalytic property

Three new organic–inorganic supramolecular hybrids, namely, (2-C5H7N2)4(PMo12O40)2·(2-C5H6N2)6·(C4H8N4)·H2O (compound 1), (3-C5H7N2)6·(PMo12O40)2·(3-C5H6N2)4·H8O4·(H2O)8 (compound 2), (4-C5H7N2)6(PMo12O40)2·(4-C5H6N2)4·(C4H6N3) (compound 3), have been synthesized by hydrothermal method and characterized by elemental analyses, IR, UV–vis, TGA and single-crystal X-ray diffraction. Compound 1–3 constructed from Keggin polyoxoanions and 2-/3-/4-aminopyridine organic ligands, exhibit an extended three-dimensional supramolecular network via hydrogen bonding and π–π stacking interactions, while compound 2 contains a tetramolecular water clusters. compounds 1 and 3 have a higher catalytic activity for the oxidation of acetone tested in a continuous-flow fixed-bed micro-reactor. When the initial concentration of the acetone is 6.1 g m−3 in air and the flow velocity is 4.5 mL min−1, the acetone is completely eliminated at 160 °C. But compound 2 has lower catalytic activity for the oxidation of acetone.

Supramolecular graphene oxide-alkylamine hybrid materials: variation of dispersibility and improvement of thermal stability

Supramolecular hybrid materials of graphene oxide (GO) with octadecylamine or dodecylamine have been fabricated by a simple self-assembly technique at room temperature. Many characterization methods have been used to research the micelle-like nanostructures. Compared to unmodified GO, the alkyl-functionalized graphene hybrids could be easily dispersed in various nonpolar organic solvents, such as petroleum ether, n-heptane, isooctane, dimethylbenzene etc., rather than in polar solvents. It was found that alkylamine plays a key role during such preparation. Octadecanol (ODO) produced hardly any modification of GO under the conditions, because the so-called product (GO-ODO) exhibits a high degree of similarity to GO in solvent dispersion behaviour and the Fourier transform infrared spectroscopy. The addition of alkylamine significantly improves the thermal stability of the nanomaterials. The improved thermal degradation temperatures can be obtained for polyethylene glycol and polymethyl methacrylate after filling it with as little as 1 wt% of the hybrid, suggesting their great potential as novel nanofillers in industry.

Ultrafast charge separation in supramolecular tetrapyrrole–graphene hybrids

Supramolecular donor-acceptor hybrids composed of few-layer graphene as an electron acceptor and phthalocyanine or porphyrin bearing four pyrene entities as photosensitizer donors have been synthesized, and occurrence of ultrafast charge separation in the order of 10(11)-10(12) s(-1) due to close proximity of the donor and acceptor entities is demonstrated.

Non-covalent versus covalent donor–acceptor systems based on near-infrared absorbing azulenocyanines and C60 fullerene derivatives

A novel supramolecular electron donor-acceptor hybrid (2·1) and an electron donor-acceptor conjugate (3), both exhibiting a remarkably shifted Q band in the NIR region of the solar spectrum, were prepared. Irradiation of the supramolecular ensemble 2·1 within the visible range leads to a nanosecond lived radical-ion pair state Zn-azulenocyanine˙(+)-C(60)˙(-).

Immobilizing NIR absorbing azulenocyanines onto single wall carbon nanotubes—from charge transfer to photovoltaics

In this fundamental study, the supramolecular interactions between SWNTs and either symmetrical Zn(II) octa-tert-butylazulenocyanine 1 or a Zn(II) azulenocyanine-phthalocyanine 2 bearing a pyrene unit have been evaluated. The synthetic protocol allowed for the preparation of unsymmetrical azulenocyanine-phthalocyanine molecules, which incorporate reactive hydroxyl functional groups useful for the preparation of more elaborate derivatives, that is, the pyrene containing derivative 2 by an esterification reaction. To shed light onto the mutual interactions between 1 or 2 and SWNT, stable suspensions of SWNT in a mixture of 25% THF and 75% DMF were titrated with variable amounts of 1 or 2. These assays indicate a successful immobilization of azulenocyanine derivatives 1 or 2 onto SWNTs to yield the supramolecular hybrids SWNT/1 and SWNT/2. In this light, the physico-chemical properties of 1 and 2 as well as those of SWNT/1 and SWNT/2 were investigated. From these we conclude strong interactions in the ground state, and a rapid charge separation in the excited state of SWNT/1 or SWNT/2. The accordingly formed radical ion pair states decay with lifetimes of 124 and 137 ps for SWNT/1 and SWNT/2, respectively. Finally, SWNT/1 and SWNT/2 were integrated into photoelectrochemical cells, revealing a response throughout the visible and near-infrared with a moderate IPCE maxima of 2.5%.

Supramolecular block copolymers: graphene oxide composites for memory device applications

Bistable resistive switching characteristics obtained using a supramolecular hybrid route to hydrogen-bonded block copolymers (BCP) and graphene oxide (GO) as charge storage materials are reported for write-once-read-many-times (WORM) memory devices.

Photoinduced charge separation in three-layer supramolecular nanohybrids: fullerene–porphyrin–SWCNT

Photoinduced charge separation processes of three-layer supramolecular hybrids, fullerene-porphyrin-SWCNT, which are constructed from semiconducting (7,6)- and (6,5)-enriched SWCNTs and self-assembled via π-π interacting long alkyl chain substituted porphyrins (tetrakis(4-dodecyloxyphenyl)porphyrins; abbreviated as MP(alkyl)(4)) (M = Zn and H(2)), to which imidazole functionalized fullerene[60] (C(60)Im) is coordinated, have been investigated in organic solvents. The intermolecular alkyl-π and π-π interactions between the MP(alkyl)(4) and SWCNTs, in addition, coordination between C(60)Im and Zn ion in the porphyrin cavity are visualized using DFT calculations at the B3LYP/3-21G(*) level, predicting donor-acceptor interactions between them in the ground and excited states. The donor-acceptor nanohybrids thus formed are characterized by TEM imaging, steady-state absorption and fluorescence spectra. The time-resolved fluorescence studies of MP(alkyl)(4) in two-layered nanohybrids (MP(alkyl)(4)/SWCNT) revealed efficient quenching of the singlet excited states of MP(alkyl)(4) ((1)MP*(alkyl)(4)) with the rate constants of charge separation (k(CS)) in the range of (1-9) × 10(9) s(-1). A nanosecond transient absorption technique confirmed the electron transfer products, MP˙(+)(alkyl)(4)/SWCNT˙(-) and/or MP˙(-)(alkyl)(4)/SWCNT˙(+) for the two-layer nanohybrids. Upon further coordination of C(60)Im to ZnP, acceleration of charge separation via(1)ZnP* in C(60)Im→ZnP(alkyl)(4)/SWCNT is observed to form C(60)˙(-)Im→ZnP˙(+)(alkyl)(4)/SWCNT and C(60)˙(-)Im→ZnP(alkyl)(4)/SWCNT˙(+) charge separated states as supported by the transient absorption spectra. These characteristic absorptions decay with rate constants due to charge recombination (k(CR)) in the range of (6-10) × 10(6) s(-1), corresponding to the lifetimes of the radical ion-pairs of 100-170 ns. The electron transfer in the nanohybrids has further been utilized for light-to-electricity conversion by the construction of proof-of-concept photoelectrochemical solar cells.