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1.
Chemistry ; 23(70): 17663-17666, 2017 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-29105944

RESUMO

In our bodies, a slight pH change causes remarkable activation or serious damage in the biological processes and continuously keeps biological homeostasis. Detection of such a slight pH change has been a constant demand in searching for unusual biological events. In this paper, we demonstrate a novel pH sensory system that has been achieved through a combination of charge neutralization by a slight pH change with aggregation-induced emission (AIE). We selected a cyano-functionalized oligo(phenylene-vinylene) (cyanoOPV) backbone for AIE and introduced ammonium-tethered boronic acid groups as a pH-dependent function. The self-assembling of these dyes (OPV-Cn) was readily achieved by pH-dependent charge neutralization at the neutral pH region. This sensory system showed unusually sensitive pH responsiveness in a narrow pH range. Moreover, this pH change was observed in a biologically important neutral pH region. We therefore believe that this system is broadly applicable to detect the slight pH change occurring in the biological events.

2.
Angew Chem Int Ed Engl ; 56(41): 12518-12522, 2017 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-28749601

RESUMO

The newly developed oligophenylenevinylene (OPV)-based fluorescent (FL) chiral chemosensor (OPV-Me) for the representative enantiomeric guest, 1,2-cyclohexanedicarboxylic acid (1,2-CHDA: RR- and SS-form) showed the high chiral discrimination ability, resulting in the different aggregation modes of OPV-Me self-assembly: RR-CHDA directed the fibrous supramolecular aggregate, whereas SS-CHDA directed the finite aggregate. The consequent FL intensity toward RR-CHDA was up to 30 times larger than that toward SS-CHDA. Accordingly, highly enantioselective recognition was achieved. Application to the chirality sensing was also possible: OPV-Me exhibited a linear relationship between the FL intensity and the enantiomeric excess through the morphological development of stereocomplex aggregates. These results clearly show that the chiral recognition ability is manifested by the amplification cascade of the chirality difference through self-assembly.

3.
Chemistry ; 23(8): 1937-1941, 2017 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-27897341

RESUMO

The control over supramolecular interactions and obtaining information beyond the molecular scale is an extended challenge. The intriguing self-assembly of a perylene-3,4,9,10-tetracarboxylic acid diimide (PDI)-based novel bolaamphiphilic probe is experienced within an artificial environment that is restrained by using supramolecular crystallization and molecular recognition. The bolaamphiphile with a hydrophilic [18]-azacrown ether ring produced nanoaggregates due to differing solubilities in organic and aqueous media. A structural evolution was observed in the presence of alkali metal ions as guests. The metal complexes form a pseudo-cationic structure, which is further involved in an ionic self-assembly with biomolecules, thus resulting new spectroscopic information on the dye self-assembly. The overarching aim of this study is to emphasize the importance of the concept of supramolecular adaptability, which has been used to establish an environment-friendly behavior based on noncovalent forces, thus leading to the evolution of new assembly structures and photophysical properties.

4.
Data Brief ; 7: 183-187, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27761490

RESUMO

This data article provides supplementary figures to the research article entitled, "Phase separation approach to a reactive polycarbonate monolith for "click" modifications" (Xin et al., Polymer, 2015, doi:10.1016/j.polymer.2015.04.008). Here, the nitrogen adsorption/desorption isotherms of the prepared porous polycarbonate monolith are shown to classify its inner structure and calculate the specific surface area. The monoliths were modified by using the thiol-ene click chemistry and the olefin metathesis, which was examined by contact angle measurements, FT-IR, solid state 13C NMR spectroscopy as well as thermogravimetric analysis.

5.
Angew Chem Int Ed Engl ; 55(19): 5708-12, 2016 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-27060601

RESUMO

Oligophenylenevinylene (OPV)-based fluorescent (FL) chemosensors exhibiting linear FL responses toward polyanions were designed. Their application to FL sensing of glycosaminoglycans (heparin: HEP, chondroitin 4-sulfate: ChS, and hyaluronic acid: HA) revealed that the charge density encoded as the unit structure directs the mode of OPV self-assembly: H-type aggregate for HEP with 16-times FL increase and J-type aggregate for HA with 93-times FL increase, thus unexpectedly achieving the preferential selectivity for HA in contrast to the conventional HEP selective systems. We have found that the integral magnitude of three factors consisting of binding mechanism, self-assembly, and FL response can amplify the structural information on the target input into the characteristic FL output. This emergent property has been used for a novel molecular recognition system that realizes unconventional FL sensing of HA, potentially applicable to the clinical diagnosis of cancer-related diseases.


Assuntos
Corantes Fluorescentes/química , Glicosaminoglicanos/química , Ácido Hialurônico/química , Espectrometria de Fluorescência , Sulfatos de Condroitina/química , Heparina/química , Concentração de Íons de Hidrogênio
6.
Phys Chem Chem Phys ; 18(19): 13239-45, 2016 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-27118684

RESUMO

Long-term creative approaches have been considered in the design of molecular probes to overcome the quenching effect of important dyes in an aqueous medium. Using the rational donor-acceptor based design principle, we demonstrate herein the different fluorescence states of a non-conjugated symmetrical perylene-azacrown ether system in a solution, from the molecular to the aggregated states. The ethylene-spacer is exceptionally capable of fluorescence enhancement, even in the aggregated state (organic nanoparticle, ONPs, 44 nm), overcoming the quenching effect on changing the solvent from tetrahydrofuran to water. The ONPs with crown ether receptors at the surface show colloidal stability in an aqueous solution. Furthermore, an improved fluorescent state is developed via ONPs-polymer (protamine, Pro) hybridization. Supramolecular interactions between the crown ring and the guanidinium group in Pro play an important role in the ONPs-Pro hybrid formation. The decorated fluorescent hybrid state is finally used as a nano-probe for sensing heparin via the turn-OFF mechanism. The decoration method is further generalized by recognition of the nucleotides. Herein, we detail the bottom-up approach to the molecular design and development of the different fluorescent states of a useful probe. Most excitingly, this new approach is very general and adaptive to facile detection.

7.
Photochem Photobiol Sci ; 13(7): 997-1004, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24887701

RESUMO

The investigated multiterpyridine chromophores form a 2D network upon metal ion complexation that causes profound changes to their photophysical properties; the experimental results are complemented by modeling of the electronic properties of isolated monomers as well as the structure of the polymeric network.

8.
J Am Chem Soc ; 136(16): 6103-10, 2014 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-24673195

RESUMO

Monolayer sheets have gained attention due to the unique properties derived from their two-dimensional structure. One of the key challenges in sheet modification/synthesis is to exchange integral parts while keeping them intact. We describe site-to-site transmetalation of Zn(2+) in the netpoints of cm(2)-sized, metal-organic sheets by Fe(2+), Co(2+), and Pb(2+). This novel transformation was done both randomly and at predetermined patterns defined by photolithography to create monolayer sheets composed of different netpoints. All transmetalated sheets are mechanically strong enough to be spanned over 20 × 20 µm(2) sized holes. Density functional theory calculations provide both a model for the molecular structure of an Fe(2+)-based sheet and first insights into how transmetalation proceeds. Such transmetalated sheets with random and patterned netpoints can be considered as two-dimensional analogues of linear copolymers. Their nanoscale synthesis presents an advance in monolayer/polymer chemistry with applications in fields such as surface coating, molecular electronics, device fabrication, imaging, and sensing.

9.
Adv Mater ; 26(13): 2052-8, 2014 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-24347495

RESUMO

Covalent monolayer sheets in 2 hours: spreading of threefold anthracene-equipped shape-persistent and amphiphilic monomers at the air/water interface followed by a short photochemical treatment provides access to infinitely sized, strictly monolayered, covalent sheets with in-plane elastic modulus in the range of 19 N/m.

10.
Macromol Rapid Commun ; 34(21): 1670-80, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24115363

RESUMO

Oligofunctional terpyridine-based monomers are spread at an air/water interface, where they are connected with transition metal salts such as Fe(II) into mechanically coherent monolayer sheets of macroscopic dimension. The conversions of these processes are determined by XPS for several monomer/metal ion combinations. The sheets are transferred onto TEM grids, the 20 × 20 square micrometer sized holes of which can be spanned. AFM indentation experiments provide in-plane elastic moduli which are compared with naturally occurring sheets such as graphene. The new organometallic sheets are also used to create multilayer assemblies on square centimeter length scales on solid substrates. Finally some directions are provided where this research can lead to in future and where its application potential lies.


Assuntos
Compostos Ferrosos/química , Piridinas/química , Modelos Moleculares , Estrutura Molecular , Tamanho da Partícula , Propriedades de Superfície
11.
J Am Chem Soc ; 135(38): 14134-41, 2013 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-24044739

RESUMO

A two-dimensional polymer (2DP) based on the dimerization of anthraceno groups arranged in a triptycene motif is reported. A photoinduced polymerization is performed in the crystalline state and gives a lamellar 2DP via a crystal-to-crystal (but not single-crystal to single-crystal) transformation. Solvent-induced exfoliation provides monolayer sheets of the 2DP. The 2DP is considered to be a tiling, a mathematical approach that facilitates structural elucidation.

12.
Chemistry ; 19(40): 13348-54, 2013 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-24038419

RESUMO

The synthesis of four shape-persistent macrocycles with three 1,8-diazaanthracene units each is reported (2,3 a-3 c). For two of them single crystals could be obtained and the structures in the crystal be solved. The structures reveal that macrocycle 2 self-dimerizes in the solid state; surprisingly it also forms a stable dimer in solution. The reason for this is seen in unusually efficient dispersion interactions as a consequence of the large contact areas in the dimer. All macrocycles are assessed as to their applicability in lateral polymerizations in the single crystal as well as in solution.

13.
Chimia (Aarau) ; 67(4): 283-5, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23967707

RESUMO

We describe the challenges involved with extending the limited lateral size of two-dimensional polymers (2DPs). An amphiphilic monomer with three-fold symmetry is chosen to form an ideally tessellated monolayer at the air/water interface. Anthracene [4+4] photo-dimerization is chosen as the growth reaction. Formation of covalent net-points upon anthracene dimerization has an influence on the mechanical coherence of the resulting sheets which could be investigated qualitatively and quantitatively by means of AFM nano-indentation.


Assuntos
Antracenos/química , Polímeros/química , Dimerização , Microscopia de Força Atômica , Estrutura Molecular , Propriedades de Superfície
14.
J Am Chem Soc ; 134(28): 11721-5, 2012 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-22694341

RESUMO

A macrocyclic monomer with two opposing 1,8-diazaanthracene units is polymerized in a single crystal by a photochemically induced [4 + 4] cycloaddition reaction between neighboring monomers in which the anthracene units are stacked face-to-face at the critical Schmidt distance. The severe structural changes associated with this are minimized by the monomer design, wherein the linkers between the two opposing photoreactive 1,8-diazaanthracene units are connected to the 4 and 5 positions of the latter, whose spatial positioning is changed the least during dimerization. This helps to keep the monomer's overall shape basically unchanged during the polymerization. The resulting new rigid-rod polymer is soluble in its protonated form, and after counterion exchange with a surfactant, it can be depolymerized back into monomer upon relatively mild thermal treatment (120 °C) in an organic solvent.

15.
Nat Chem ; 4(4): 287-91, 2012 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-22437713

RESUMO

Synthetic polymers are widely used materials, as attested by a production of more than 200 millions of tons per year, and are typically composed of linear repeat units. They may also be branched or irregularly crosslinked. Here, we introduce a two-dimensional polymer with internal periodicity composed of areal repeat units. This is an extension of Staudinger's polymerization concept (to form macromolecules by covalently linking repeat units together), but in two dimensions. A well-known example of such a two-dimensional polymer is graphene, but its thermolytic synthesis precludes molecular design on demand. Here, we have rationally synthesized an ordered, non-equilibrium two-dimensional polymer far beyond molecular dimensions. The procedure includes the crystallization of a specifically designed photoreactive monomer into a layered structure, a photo-polymerization step within the crystal and a solvent-induced delamination step that isolates individual two-dimensional polymers as free-standing, monolayered molecular sheets.


Assuntos
Polímeros/síntese química , Antracenos/química , Cristalização , Microscopia de Força Atômica , Polímeros/química , Solventes/química
17.
Org Lett ; 12(12): 2778-81, 2010 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-20499923

RESUMO

New macrocyclic amphiphiles with two or three integrated 1,8-anthrylenes have been synthesized by an iterative Sonogashira cross-coupling protocol. The final cyclization has been conducted with 80% yield under cuprous-free dilution conditions. Formation of a monolayer at the air/water interface has also been demonstrated. These results open the intriguing possibility to construct large 2D supramolecular/macromolecular systems for which unique photophysical and -chemical properties are expected.

18.
Langmuir ; 25(16): 8845-8, 2009 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-19719210

RESUMO

4-phenylazophenyl methacrylate (AzoMA) and benzyl methacrylate (BnMA) were copolymerized to produce multistimuli-responsive polymers (P(AzoMA-r-BnMA)s) in a hydrophobic ionic liquid (IL), 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide ([C2mim][NTf2]), as the solvent. P(AzoMA-r-BnMA)s with a maximum of ca. 4 mol % AzoMA were soluble in [C2mim][NTf2] at low temperatures, and they underwent lower critical solution temperature (LCST) phase separation with an increase in temperature. Under UV and visible light irradiation, P(AzoMA-r-BnMA)s underwent reversible photochromism of trans-to-cis and cis-to-trans isomerization, respectively. The LCST temperature differences between trans- and cis-form polymers in the IL were as large as 22 degrees C. Reversible photoinduced phase separation of the polymers was achieved at a certain temperature; at this temperature, the cis-form polymers were soluble in the IL, but the trans-form polymers were not.


Assuntos
Compostos Azo/química , Líquidos Iônicos/química , Polímeros/química , Isomerismo , Estrutura Molecular , Transição de Fase , Fotoquímica , Temperatura
19.
Org Lett ; 11(18): 4112-5, 2009 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-19678688

RESUMO

Two straight monomers were subjected to an AA/BB-type Suzuki polycondensation with a hairpin-shaped 1,8-anthrylene monomer as the counterpart leading to a novel polyarylene which should have the preferred conformation of a folded chain. The molar masses were determined by gel permeation chromatography and dynamic light scattering and found to be M(w) = 14,000 and M(n) = 7,000. MALDI-TOF MS analysis of a fraction provides a fingerprint of the step-growth nature of this polymerization.

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