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1.
Artigo em Inglês | MEDLINE | ID: mdl-32170796

RESUMO

Incorporation of non-equilibrium actions in the sequence of self-assembly processes would be an effective means to establish bio-like high functionality hierarchic assemblies. As a novel methodology beyond self-assembly, nanoarchitectonics, which has as its aim the fabrication of functional materials systems from nanoscopic units through the methodological fusion of nanotechnology with other scientific disciplines including organic synthesis, supramolecular chemistry, microfabrication, and bio-process, has been applied to this strategy. The application of non-equilibrium factors to conventional self-assembly processes is discussed on the basis of examples of directed assembly, Langmuir-Blodgett assembly, and layer-by-layer assembly. In particular, examples of the fabrication of hierarchic functional structures using bio-active components such as proteins or by the combination of bio-components and two-dimensional nanomaterials, are described. Methodologies described in this review article highlight possible approaches using the nanoarchitectonics concept beyond self-assembly for creation of bio-like higher functionalities and hierarchic structural organization.

2.
Chem Commun (Camb) ; 56(27): 3855-3858, 2020 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-32134092

RESUMO

A directly linked BODIPY-oxoporphyrinogen dyad has been newly synthesized and occurrence of sequential photoinduced energy and electron transfer upon fluoride anion binding to oxoporphyrinogen has been demonstrated by spectral, electrochemical and femtosecond transient absorption studies.

3.
Chem Asian J ; 15(3): 406-414, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-31922659

RESUMO

Molecular functions depend on conformations and motions of the corresponding molecular species. An air-water interface is a suitable asymmetric field for the control of molecular conformations and motions under a small applied force. In this work, double-paddled binuclear PtII complexes containing pyrazole rings linked by alkyl spacers were synthesized and their orientations and emission properties dynamically manipulated at the air-water interface. The complexes emerge from water with concurrent variation of interface orientation of the planes of the PtII complexes from perpendicular to parallel during mechanical compression suggesting a unique 'submarine emission'. Phosphorescence of the complexes is quenched at the air-water interface prior to monolayer formation with intensities subsequently rapidly increasing during monolayer compression. These results indicate that asymmetric reactions and motions might be controlled by applying mechanical force at the air-water interface.

4.
Adv Mater ; 32(4): e1905942, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31814174

RESUMO

There is a growing interest in the development of dynamic adaptive biomaterials for regulation of cellular functions. However, existing materials are limited to two-state switching of the presentation and removal of cell-adhesive bioactive motifs that cannot emulate the native extracellular matrix (ECM) in vivo with continuously adjustable characteristics. Here, tunable adaptive materials composed of a protein monolayer assembled at a liquid-liquid interface are demonstrated, which adapt dynamically to cell traction forces. An ultrastructure transition from protein monolayer to hierarchical fiber occurs through interfacial jamming. Elongated fibronectin fibers promote formation of elongated focal adhesion structures, increase focal adhesion kinase activation, and enhance neuronal differentiation of stem cells. Cell traction force results in spatial rearrangement of ECM proteins, which feeds back to alter stem cell fate. The reported biomimetic adaptive liquid interface enables dynamic control of stem cell behavior and has potential translational applications.

5.
ACS Nano ; 13(12): 14005-14012, 2019 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-31794176

RESUMO

We report the production of fullerene microtubes (FMTs), having solid cores bisecting their tubular cavities, from solutions of mixtures of fullerene C60 and C70 and have demonstrated the structural transformation of FMTs to fullerene microhorns (FMHs) upon their exposure to alcohol/mesitylene mixtures at 25 °C. The conically shaped microhorns have hollow interiors and exhibit preferential recognition of silica particles over fullerene C70, polystyrene (PS) latex, PS hydroxylate, or PS carboxylate particles of similar dimensions due to strong electrostatic interactions between negatively charged FMHs and positively charged silica particles.

6.
J Am Chem Soc ; 141(50): 19570-19574, 2019 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-31736293

RESUMO

Peripherally substituted tetradecaazaheptacene (N14Hp) compounds, exhibiting amphiprotism-coupled emission, have been synthesized. X-ray crystallography reveals a planar acene-like chromophore, and electronic absorption and emission occur in the near-infrared biological transparency window (650-900 nm). The compounds exhibit long-wavelength emission with photoluminescence quantum yields ΦPL up to ∼0.61 at 686 nm, with the monodeprotonated state ΦPL ≈ 0.58 at 712 nm. This unprecedented highly nitrogenous chromophore illustrates the stability and utility of the pyrazinacenes for different applications based on their photophysical properties and chemical structures.

7.
Dalton Trans ; 48(41): 15583-15596, 2019 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-31353382

RESUMO

Interactions of anionic guests with a tritopic peripherally functionalized conjugated calix[4]pyrrole host (1) prepared using a regioselective synthetic method is reported. The regioselectivity of synthesis relies on selective N-alkylation of the calix[4]pyrrole caused by peripheral substitution of one pyrrole group with subsequent N-alkylation at the opposing pyrrole group termed by us 'knock-on' regioselectivity. The resulting host molecule exhibits anion interactions with common chloride and nitrate anions enhanced by an order of magnitude over the parent conjugated calix[4]pyrrole. Combined analysis of 1H NMR and UV-vis spectroscopic titration data enabled an evaluation of binding strengths of anions with the host KA in a binding model where the salt dissociation process is also incorporated in the form of its dissociation constant Kd. Anions could be classified as two types based on their interactions with 1: Type A anions (chloride, nitrate, perchlorate, hydrogensulphate) associate as 1 : 1 complexes through hydrogen bonding while interactions involving Type B anions (acetate, fluoride, dihydrogenphosphate) are complicated by host deprotonation and/or countercation association. Hosts based on rim-functionalized calix[4]pyrroles such as 1 represent a promising new family of chromophores for estimation of biologically relevant anions or other species.

8.
Nat Commun ; 10(1): 1007, 2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-30824697

RESUMO

Molecules that can exist in multiple states with the possibility of toggling between those states based on different stimuli have potential for use in molecular switching or sensing applications. Multimodal chemical or photochemical oxidative switching of an antioxidant-substituted resorcinarene macrocycle is reported. Intramolecular charge-transfer states, involving hemiquinhydrones are probed and these interactions are used to construct an oxidation-state-coupled molecular switching manifold that reports its switch-state conformation via striking variation in its electronic absorption spectra. The coupling of two different oxidation states with two different charge-transfer states within one macrocyclic scaffold delivers up to five different optical outputs. This molecular switching manifold exploits intramolecular coupling of multiple redox active substituents within a single molecule.

9.
Sci Technol Adv Mater ; 20(1): 51-95, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30787960

RESUMO

The development of science and technology of advanced materials using nanoscale units can be conducted by a novel concept involving combination of nanotechnology methodology with various research disciplines, especially supramolecular chemistry. The novel concept is called 'nanoarchitectonics' where self-assembly processes are crucial in many cases involving a wide range of component materials. This review of self-assembly processes re-examines recent progress in materials nanoarchitectonics. It is composed of three main sections: (1) the first short section describes typical examples of self-assembly research to outline the matters discussed in this review; (2) the second section summarizes self-assemblies at interfaces from general viewpoints; and (3) the final section is focused on self-assembly processes at interfaces. The examples presented demonstrate the strikingly wide range of possibilities and future potential of self-assembly processes and their important contribution to materials nanoarchitectonics. The research examples described in this review cover variously structured objects including molecular machines, molecular receptors, molecular pliers, molecular rotors, nanoparticles, nanosheets, nanotubes, nanowires, nanoflakes, nanocubes, nanodisks, nanoring, block copolymers, hyperbranched polymers, supramolecular polymers, supramolecular gels, liquid crystals, Langmuir monolayers, Langmuir-Blodgett films, self-assembled monolayers, thin films, layer-by-layer structures, breath figure motif structures, two-dimensional molecular patterns, fullerene crystals, metal-organic frameworks, coordination polymers, coordination capsules, porous carbon spheres, mesoporous materials, polynuclear catalysts, DNA origamis, transmembrane channels, peptide conjugates, and vesicles, as well as functional materials for sensing, surface-enhanced Raman spectroscopy, photovoltaics, charge transport, excitation energy transfer, light-harvesting, photocatalysts, field effect transistors, logic gates, organic semiconductors, thin-film-based devices, drug delivery, cell culture, supramolecular differentiation, molecular recognition, molecular tuning, and hand-operating (hand-operated) nanotechnology.

10.
Small ; 15(5): e1804640, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30624030

RESUMO

Mechanical cues of cellular microenvironments can modulate cell functions including cell spreading and differentiation. Most studies of cellular functions are performed using a solid substrate, and it is thought that cells cannot spread on fluid substrates because of rapid relaxation, which cannot resist against actomyosin-based cell contractility. Here, the spreading and growth of anchorage-dependent cells such as human mesenchymal stem cells at the liquid interface between a perfluorocarbon fluid and the culture medium are observed. It is demonstrated that a monomolecular protein nanosheet self-assembled at a fluid interface is sufficiently rigid to support cell spreading without additional treatment. Fine tuning of the packing of these proteins at the liquid interface permits tailoring of the mechanics of the protein layer, ultimately allowing for the regulation of cell spreading. The greater stiffness of the protein nanosheets triggers cell spreading, adhesion growth, and yes-associated protein nuclear translocation. Cell behavior at the fluid interface is explained within the framework of the molecular clutch model. In addition, the freestanding ultrathin protein nanosheets are extremely flexible, easily deformed, and perceived by cells as being much softer. The findings are expected to provide a new perspective for insights into cell-material interactions.

11.
ACS Nano ; 13(2): 2410-2419, 2019 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-30673207

RESUMO

The intramolecular rotation of 4-farnesyloxyphenyl-4,4-difluoro-4-bora-3a,4a-diaza- s-indacene (BODIPY-ISO) was controlled by tuning its local physical environment within a mixed self-assembled monolayer at an air-water interface. Intramolecular rotation was investigated by considering the twisted intramolecular charge transfer (TICT) fluorescence of BODIPY-ISO, which increases in intensity with increasing viscosity of the medium. In situ fluorescence spectroscopy was performed on mixed monolayers of BODIPY-ISO with several different lipids at the air-water interface during in-plane compression of the monolayers. Depending on the identity of the lipid used, the fluorescence of the mixed monolayers could be enhanced by mechanical compression, indicating that the rotation of BODIPY-ISO can be controlled dynamically in mixtures with lipids dispersed at the air-water interface. Taken together, our findings provide insight into strategies for controlling the dynamic behavior of molecular machines involving mechanical stimuli at interfaces.

12.
Phys Chem Chem Phys ; 20(27): 18873-18878, 2018 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-29968876

RESUMO

A hierarchical heterostructure composed of silver nanoparticles (Ag-NPs: average diameter ∼10 nm) on fullerene nanorods (FNRs: average length ∼11 µm and average diameter ∼200 nm) was fabricated using a simple solution route. It was used as an effective single particle freestanding surface enhanced Raman scattering (SERS) substrate for the detection of target molecules (Rhodamine 6G: R6G). FNRs were formed ultra-rapidly (formation process completed in a few seconds) at a liquid-liquid interface of methanol and C60/mesitylene solution then Ag-NPs were grown directly on the surfaces of the FNRs by treatment with a solution of silver nitrate in ethanol. This unique hierarchical heterostructure allows efficient adsorption of target molecules also acting as an effective SERS substrate capable of detecting the adsorbed R6G molecules in the nanomolar concentration range. In this study, SERS spectra are acquired on an isolated single Ag-FNR for the detection of the absorbed molecule rather than from a bulk, large area film composed of silver/gold nanoparticles as used in conventional methods. Thus, this work provides a new approach for the design and fabrication of freestanding SERS substrates for molecular detection applications.

13.
ChemistryOpen ; 7(5): 323-335, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29744284

RESUMO

Herein, we modulate the chromic response of a highly colored tetrapyrrole macrocycle, namely, tetrakis(3,5-di-tert-butyl-4-oxocyclohexadien-2,5-yl)porphyrinogen (OxP) by structural modification. N-Benzylation at the macrocyclic nitrogen atoms leads to stepwise elimination of the two calix[4]pyrrole-type binding sites of OxP and serial variation of the chromic properties of the products, double N-benzylated Bz2OxP and tetra N-benzylated Bz4OxP. The halochromic (response to acidity) and solvatochromic (response to solvent polarity) properties were studied by using UV/Vis spectroscopy and NMR spectroscopy in nonpolar organic solvents. Titration experiments were used to generate binding isotherms to elucidate their binding properties with difluoroacetic acid. Differences in the halochromic properties of the compounds allowed construction of a colorimetric scale of acidity in nonpolar solvents, as the compounds in the series OxP, Bz2OxP, and Bz4OxP are increasingly difficult to protonate but maintain their propensity to change color upon protonation. The concurrent effects of binding-site blocking and modulation of acidity sensitivity are important new aspects for the development of colorimetric indicators.

14.
J Phys Chem B ; 122(19): 5114-5120, 2018 05 17.
Artigo em Inglês | MEDLINE | ID: mdl-29688722

RESUMO

The use of chiral auxiliaries, which derivatize enantiomers to diastereomers, is an established technique for NMR spectroscopic analysis of chirality and enantiomeric excess ( ee). Here we report that some small prochiral molecules exhibit ee-dependent splitting of 1H NMR signals at room temperature based on acid/base interactions with chiral analytes, especially when either a chiral or prochiral acid contains a phenoxy group at the α-position of the carboxylic acid. As a representative case, the benzylamine (BA)/2-phenoxylpropionic acid (PPA) complex was comprehensively investigated by using various methods. Notably, X-ray crystallographic analysis shows that there are multipoint interactions in the BA/PPA complex, implying that "fixing" of molecular conformation is critical for efficient intermolecular transfer of magnetic anisotropy. Our results suggest that a wide range of prochiral molecules are available for NMR determination of ee when intermolecular interactions between prochiral molecules and chiral analytes are adequately designed.

15.
Beilstein J Nanotechnol ; 9: 801-808, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29600141

RESUMO

Pure graphene in the form of few-layer graphene (FLG) - 1 to 6 layers - is biocompatible and non-cytotoxic. This makes FLG an ideal material to incorporate into dental polymers to increase their strength and durability. It is well known that graphene has high mechanical strength and has been shown to enhance the mechanical, physical and chemical properties of biomaterials. However, for commercial applicability, methods to produce larger than lab-scale quantities of graphene are required. Here, we present a simple method to make large quantities of FLG starting with commercially available multi-layer graphene (MLG). This FLG material was then used to fabricate graphene dental-polymer composites. The resultant graphene-modified composites show that low concentrations of graphene (ca. 0.2 wt %) lead to enhanced performance improvement in physio-mechanical properties - the mean compressive strength increased by 27% and the mean compressive modulus increased by 22%. Herein we report a new, cheap and simple method to make large quantities of few-layer graphene which was then incorporated into a common dental polymer to fabricate graphene-composites which shows very promising mechanical properties.

16.
Chem Commun (Camb) ; 54(11): 1351-1354, 2018 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-29350717

RESUMO

A bis-crown ether-oxoporphyrinogen was newly synthesized and self-assembled concurrently with C60 alkyl ammonium cations at the crown ether sites and F- anions (through hydrogen bonding) at the oxoporphyrinogen core. Ultrafast photoinduced charge transfer processes within the donor-acceptor conjugate were promoted by fluoride ion binding and this was established using various spectroscopic methods and transient absorption studies.

17.
Phys Chem Chem Phys ; 20(4): 2761-2770, 2018 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-29322126

RESUMO

Hollow nanocapsules (named Hybridosomes®) possessing a polymer/nanoparticle shell were used to covalently construct hybrid films in a one-pot fashion. The alkyne bearing organic/inorganic Hybridosomes® were reticulated with azide bearing homobifunctional polyethyleneglycol (PEG) linkers, by using an electro-click reaction on F-SnO2 (FTO) electrodes. The coatings were obtained by promoting the Cu(i)-catalyzed click reaction between alkyne and azide moieties in the vicinity of the electrode by the electrochemical generation of Cu(i) ions. The physicochemical properties of the covalently reticulated hybrid films obtained were studied by SEM, AFM, UV-vis and fluorescence spectroscopy. The one-pot covalent click reaction between the nanocapsules and the PEG linkers in the film did not affect the desirable features of the Hybridosomes® i.e. their hollow nanostructure their chemical versatility and their pH-sensitivity. Consequently, both the composition and the cargo-loading of the Hybridosomes® films could be tuned, demonstrating the versatility of these hybrid coatings. For example, the Hybridosome® films were used to encapsulate and release a bodipy fluorescent probe in response to either a pH drop or the application of an oxidative +1 V potential (vs. Ag/AgCl) at the substrate. By advancing the field of electro-synthesized films a step further toward the design of complex physicochemical interfaces, these results open perspectives for multifunctional coatings where chemical versatility, controllable stability and a hollow nanostructure are required.

18.
ACS Omega ; 3(9): 11865-11873, 2018 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31459272

RESUMO

Poly(N-isopropylacrylamide) (PNIPAM) is an important polymer with stimuli-responsive properties, making it suitable for various uses. Phase behavior of the temperature-sensitive PNIPAM polymer in the presence of four low-molecular weight additives tert-butylamine (t-BuAM), tert-butyl alcohol (t-BuOH), tert-butyl methyl ether (t-BuME), and tert-butyl methyl ketone (t-BuMK) was studied in water (D2O) using high-resolution nuclear magnetic resonance (NMR) spectroscopy and dynamic light scattering. Phase separation was thermodynamically modeled as a two-state process which resulted in a simple curve which can be used for fitting of NMR data and obtaining all important thermodynamic parameters using simple formulas presented in this paper. The model is based on a modified van't Hoff equation. Phase separation temperatures T p and thermodynamic parameters (enthalpy and entropy change) connected with the phase separation of PNIPAM were obtained using this method. It was determined that T p is dependent on additives in the following order: T p(t-BuAM) > T p(t-BuOH) > T p(t-BuME) > T p(t-BuMK). Also, either increasing the additive concentration or increasing pK a of the additive leads to depression of T p. Time-resolved 1H NMR spin-spin relaxation experiments (T 2) performed above the phase separation temperature of PNIPAM revealed high colloidal stability of the phase-separated polymer induced by the additives (relative to the neat PNIPAM/D2O system). Small quantities of selected suitable additives can be used to optimize the properties of PNIPAM preparations including their phase separation temperatures, colloidal stabilities, and morphologies, thus improving the prospects for the application.

19.
Phys Chem Chem Phys ; 20(5): 3073-3078, 2018 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-28759061

RESUMO

Intramolecular rotation of molecules contained in a two-dimensional monolayer or a three-dimensional collapsed film at an air-water interface was investigated by in situ fluorescence spectroscopy of twisted intramolecular charge transfer (TICT) type 9-(2-carboxy-2-cyanovinyl)julolidine (CCVJ) derivatives. The TICT type molecules, CCVJ-C12 and CCVJ-Chol, that contain a linear alkyl dodecyl chain or a cholesteryl group, respectively, as their hydrophobic group, were designed and synthesized to manipulate them at the air-water interface. These lipophilized molecular rotors showed the general properties of TICT molecules in solutions that the fluorescence intensity increases with increasing viscosity of the solvent, which is induced by inhibition of internal molecular rotations. The molecular rotors CCVJ-C12 and CCVJ-Chol formed monolayers at the air-water interface and in situ fluorescence spectroscopy was performed during the in-plane compression of the monolayers. It was revealed that the monomer emissions were suppressed and only after the collapse of monolayers, excimer emission from both layers consisting of CCVJ-C12 or CCVJ-Chol was observed. Suppressed monomer emission from monolayers suggests that intramolecular rotation is not inhibited in dense ordered monolayers. Furthermore, fluorescence spectroscopy of Langmuir-Blodgett (LB) films indicated that molecular rotations are not inhibited in the monolayer transferred on the solid substrates.

20.
ACS Appl Mater Interfaces ; 9(51): 44458-44465, 2017 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-29210263

RESUMO

Fullerene C60 microbelts were fabricated using the liquid-liquid interfacial precipitation method and converted into quasi 2D mesoporous carbon microbelts by heat treatment at elevated temperatures of 900 and 2000 °C. The carbon microbelts obtained by heat treatment of fullerene C60 microbelts at 900 °C showed excellent electrochemical supercapacitive performance, exhibiting high specific capacitances ca. 360 F g-1 (at 5 mV s-1) and 290 F g-1 (at 1 A g-1) because of the enhanced surface area and the robust mesoporous framework structure. Additionally, the heat-treated carbon microbelt showed good rate performance, retaining 49% of capacitance at a high scan rate of 10 A g-1. The carbon belts exhibit super cyclic stability. Capacity loss was not observed even after 10 000 charge/discharge cycles. These results demonstrate that the quasi 2D mesoporous carbon microbelts derived from a π-electron-rich carbon source, fullerene C60 crystals, could be used as a new candidate material for electrochemical supercapacitor applications.

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