Storage and Processing of Information Using Molecules: The All-Photonic Approach with Simple and Multi-Photochromic Switches

The use of photochromes for the implementation of molecular logic operations is a very promising approach toward molecular computing. This statement is based on a) the possibility of operating such molecular devices exclusively with photonic signals and b) spatiotemporally and remotely controlled switching, which is characteristic for photochromes. Herein, a brief overview of the application of simple photochromes and multi-photochromic conjugates for the small-scale functional integration of complicated logic circuits is given. This complements and extends efforts to design molecular photochromic memories for data storage described by many research groups worldwide.     

荧光分子开关的研究进展

荧光分子开关是超分子化学领域的研究热点之一,本文根据开关动作完成的方式对近年来研究的各类荧光分子开关进行了简要的归类总结,并介绍了一些具有特殊功能的荧光分子开关器件．     

Observing Proteins as Single Molecules Encapsulated in Surface‐Tethered Polymeric Nanocontainers

Protein unfolding inside immobilized polymerosomes : One of the most interesting properties of polymeric vesicles is their remarkable stability against extreme temperatures and osmotic stress, and their longevity even under harsh environmental conditions. We have demonstrated, in an application on protein folding, that surface‐tethered polymerosomes are suitable for performing time‐resolved single molecule studies with encapsulated proteins, as illustrated here.

     

Photoinitiating free‐radical polymerization electron‐transfer pairs applying amino acids and sulfur‐containing amino acids as electron donors

A series of free‐radical polymerization initiation systems, based on xanthene dyes as the absorbing chromophores [Rose bengal derivative, 3‐(3‐methylbutoxy)‐5,7‐diiodo‐6‐fluorone and 3‐acetoxy‐2,4,5,7‐tetraiodo‐6‐fluorone] and sulfur‐containing amino acids as the electron donors, were investigated. The photoredox pair xanthene dye/sulfur‐containing amino acid was effectively used for photoinitiation of free‐radical polymerization of the mixture composed of poly(ethylene glycol)diacrylate–1% NH₄OH (3 : 1). The highest initiating efficiencies were observed for the system composed of methionine derivatives as the electron donor. The mechanism of photoinduced electron transfer between sulfur‐containing amino acids and triplet state of xanthene dye was investigated using laser‐flash and steady‐state photolysis techniques. Based on photochemistry of xanthene dyes, photochemistry of sulfur‐containing amino acids, and obtained results, the mechanism describing the major processes occurring during the photoinitiated polymerization by a photoinduced intermolecular electron‐transfer process was postulated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 358–365, 2005     

Donor-Acceptor Hybrids for Organic Electronics

This review deals with functional molecules able to transfer one electron from the donor to the acceptor moiety upon light irradiation. Donor-bridge-acceptor molecular systems are of interest for a wide variety of applications, namely artificial photosynthetic architectures and materials for organic photovoltaic devices. In the respective sections, we have addressed some of the most recent and remarkable examples to explain the construction of artificial photosynthetic systems by means of a variety of remarkable photo- and electro-active electron donor molecules covalently or supramolecularly connected to a fullerene unit as the electron acceptor unit. We have also systematically reviewed the most efficient fullerene derivatives used for photovoltaic applications by blending with different semiconducting organic polymers or small molecules, affording all-organic solar cells.     

4-Amino-1,8-naphthalimide based fluorescent photoinduced electron transfer (PET) pH sensors as liposomal cellular imaging agents: The effect of substituent patterns on PET directional quenching

Four new fluorescent sensors (1-4) based on the 4-amino-1,8-naphthalimide fluorophores (Naps) have been synthesized based on the classical fluorophore-spacer-receptor model. These four compounds all gave rise to emission bands centred at ca. 535 nm, which were found to be highly pH dependent, the emission being ‘switched on’ in acidic media, while being quenched due to PET from the amino moieties to the excited state of the Nap at more alkaline pH. The luminescent pH dependence for these probes was found to be highly dependent on the substitution on the imide site, as well as the polyamine chain attached to the position 4-amino moiety. In the case of sensor 2 the presence of the 4-amino-aniline dominated the pH dependent quenching. Nevertheless, at higher pH, PET quenching was also found to occur from the polyamine site. Hence, 2 is better described as a receptor₁-spacer₁-fluorophore-spacer₂-receptor₂ system, where the dominant PET process is due to (normally less favourable) ‘directional’ PET quenching from the 4-amino-aniline unit to the Nap site. Similar trends and pH fluorescence dependences were also seen for 3 and 4. These compounds were also tested for their imaging potential and toxicity against HeLa cells (using DRAQ5 as nuclear stain which does now show pH dependent changes in acidic and neutral pH) and the results demonstrated that these compounds have reduced cellular viability at moderately high concentrations (with IC₅₀ values between ca. 8–30 µmol∙L⁻¹), but were found to be suitable for intracellular pH determination at 1 µmol∙L⁻¹concentrations, where no real toxicity was observed. This allowed us to employ these as lysosomal probes at sub-toxic concentrations, where the Nap based emission was found to be pH depended, mirroring that seen in aqueous solution for 1-4, with the main fluorescence changes occurring within acidic to neutral pH.     

阳离子荧光敏感器的器件化问题研究

通过对石英玻片表面修饰，制作了联有多氨基链萘基的超薄膜荧光敏感器件，研究了它在镍、铜等金属离子水溶液及有机溶剂中的荧光猝灭现象。发现其荧光光谱无论在水或其他有机溶剂中都存在着单体和激基缔合物（excimer)的发射峰，当处于镍离子水溶液中时，其单体峰随离子浓度的增大出现了先增强后减弱的现象，而激基缔合物的发光峰则仅略有减弱但变化不大。在铜离子水溶液中其荧光的变化情况和镍离子有所不同，对单体荧光只能观察到强度减弱的趋势，而激基缔合物则变化不大。比较了未联结的敏感器化合物分子在有机溶剂中荧光被铜离子猝灭的行为，发现与其在器件表面时有很大的差别，表明其分子结构和构象也有很大的不同。     

Building Logic into Peptide Networks: Bottom-Up and Top-Down

In this review we discuss our recent efforts directed at understanding the dynamics of catalytic networks, and their utility for performing Boolean logic operations. We start by explaining the “recipe” for the design of experimental, peptide-based, replication networks, and then the approach we take for simulating their kinetics. The studied networks can be manipulated in order to facilitate molecular replication through all 2-input Boolean logic operations, and furthermore the operational catalytic pathways can be wired together to perform more complex computational modules and network motifs. Beyond just simulations and the basic experiments, we show that while in principle all the gates may be constructed, symmetry and order constraints limit the types of logic that may be practically achieved. Finally, we describe the use of adaptive networks that form logic gates by responding to changes in the environment (pH, salt, and light), and the first steps towards realization of the performance of switching and gating molecular electronic devices using the peptides.     

2－芳基苯并噁唑的荧光猝灭和光诱导电子转移研究

本工作对两种不同的２－芳基苯并　唑化合物溶液荧光被四氯化碳所猝灭的机理进行了详细研究，通过多种途径研究表明该猝灭过程具有光诱导电子转移性质，工作还利用此电子转移所形成的活泼自由基来引发烯类单体的聚合，得到了有一定聚合度的聚甲基丙烯酸甲酯。     

Blue‐Light‐Triggered Photorelease of Active Chemicals Captured by the Flavoprotein Dodecin

Learning from nature : In nature, riboflavin binding proteins are responsible for the transport and release of riboflavin. Here, the development of a molecular photorelease system based on the riboflavin binding protein dodecin is presented. Any drug or active chemical linked to a flavin can be captured by dodecin and transported to a location of interest. Irradiation with blue light results in the release of the ligands.

     

Turn‐on chemosensors for silver ions based on oligomers with diaza‐16‐crown 6‐ether receptors and aromatic fluorophore end groups

The reaction of N‐(2,4‐dinitrophenyl)pyridinium chloride ( 1 ), diaza‐18‐crown 6‐ether (DA18C6) and 2,5‐bis(aminophenyl)‐1,3,4‐oxadiazole ( 2 ) caused the opening of the pyridinium ring and yielded an ionic oligomer (oligomer‐1) comprising a 5‐DA18C6‐penta‐2,4‐dienylideneammonium chloride main chain and 2‐(4‐aminophenyl)‐5‐phenyl‐1,3,4‐oxadiazole or 2‐(4‐N‐phenylpyridinium)‐5‐phenyl‐1,3,4‐oxadiazole end groups. Accordingly, the reaction of 1 , DA18C6 and 2,7‐diaminofluorene ( 3 ) yielded oligomer‐2. The structures of oligomer‐1 and oligomer‐2 were determined by comparing their ¹H NMR spectra with those of model compounds, which were synthesized by the 1:1 reaction of 1 with 2 or 3 . Oligomer‐1 and oligomer‐2 exhibited weak bluish‐green photoluminescence (PL) before the inclusion of Ag⁺ in the DA18C6 receptor, after which they exhibited strong bluish‐green PL. These observations can be explained by the occurrence of photoinduced electron transfer in the oligomers. Copyright © 2011 Society of Chemical Industry     

Water‐soluble dual responsive polythiophene‐g‐poly(methoxyethoxy ethyl methacrylate)‐co‐poly(N,N‐diethylamino ethyl methacrylate) for different applications

Polythiophene (PT) based dual responsive water‐soluble graft copolymer (PT‐g‐[poly(methoxyethoxy ethyl methacrylate)‐co‐poly(N,N‐diethylamino ethyl methacrylate)]) (PT‐g‐P(MeO₂MA‐co‐DEAEMA)) (PTDE) has been synthesized by random copolymerization of methoxyethoxy ethyl methacrylate (MeO₂MA) and N,N‐diethylamino ethyl methacrylate (DEAEMA) at 30 °C on the 2,5‐poly(3‐[1‐ethyl‐2‐(2‐ bromoisobutyrate)] thiophene) (PTI) macroinitiator using the Cu based atom transfer radical polymerization technique. The PTDE graft copolymer was characterized by gel permeation chromatography and ¹H NMR techniques and it exhibits thermo‐reversible solubility in water showing a lower critical solution temperature of ca 42 °C in neutral aqueous solution. The PTDE graft copolymer contains a fluorescent PT backbone, and interestingly the system exhibits doubling of fluorescence intensity with rising temperature over the temperature range 41–45 °C at pH 7. The PTDE system therefore acts following the principle of the polymeric AND logic gate and it is also found to be effective in sensing of nitroaromatics, particularly picric acid. The influence of chain hydrophobicity on the logic operation and on the sensing of nitroaromatics is discussed. © 2014 Society of Chemical Industry     

A Facile Strategy to Prepare Small Water Clusters via Interacting with Functional Molecules

Although small water clusters (SWCs) are important in many research fields, efficient methods of preparing SWCs are still rarely reported, which is mainly due to the lack of related materials and understanding of the molecular interaction mechanisms. In this study, a series of functional molecules were added in water to obtain small water cluster systems. The decreasing rate of the half-peak width in a sodium dodecyl sulfate (SDS)–water system reaches ≈20% at 0.05 mM from ¹⁷O nuclear magnetic resonance (NMR) results. Based on density functional theory (DFT) and molecular dynamics (MD) simulation calculation, it can be concluded that functional molecules with stronger negative electrostatic potential (ESP) and higher hydrophilicity have a stronger ability to destroy big water clusters. Notably, the concentrations of our selected molecule systems are one to two magnitudes lower than that of previous reports. This study provides a promising way to optimize aqueous systems in various fields such as oilfield development, protein stability, and metal anti-corrosion.     

Synthesis and photophysical behavior of a water‐soluble coumarin‐bearing polymer for proton and Ni2+ ion sensing

BACKGROUND: In recent years, many fluorescent chemosensors with various macromolecular structures have been prepared for the detection of protons or metal cations in the environment. Most of this research is focused on polymer sensors with fluorescent recognition sites in the main chain. In this case, the fluorescent recognition sites are covalently bonded to the polymer chain, and thus the polymer shows photophysical properties as a chemosensor for protons and metal ions. RESULTS: An acrylic monomer bearing coumarin moieties, 7‐hydroxy‐4‐methyl‐8‐(4′‐acryloylpiperazin‐1′‐yl)methylcoumarin, was synthesized. This was then copolymerized with N‐vinylpyrrolidone to obtain a blue fluorescent material. The fluorescent copolymer has good solubility in aqueous solution. Its main photophysical properties were determined in relation to its use as a sensor for protons and metal cations. It is an efficient ‘off‐on’ switcher for pH between 3.02 and 12.08. Additionally, the polymer sensor is selective to Ni²⁺ ions, with the increase in the fluorescence intensity depending on Ni²⁺ ion concentrations in the range 0.33 × 10^?5–7.67 × 10^?5 mol L^?1. CONCLUSION: The results suggest that this copolymer may offer potential as a reusable polymer sensor for protons and Ni²⁺ ions in aqueous solution. Copyright © 2009 Society of Chemical Industry     

Information gathering and processing with fluorescent molecules

Molecular information gathering and processing — a young field of applied chemistry — is undergoing good growth. The progress is occurring both in terms of conceptual development and in terms of the strengthening of older concepts with new examples. This review critically surveys these two broad avenues. We consider some cases where molecules emulate one of the building blocks of electronic logic gates. We then examine molecular emulation of various Boolean logic gates carrying one, two or three inputs. Some single-input gates are popular information gathering devices. Special systems, such as ‘lab-on-a-molecule’ and molecular keypad locks, also receive attention. A situation deviating from the Boolean blueprint is also discussed. Some pointers are offered for maintaining the upward curve of the field.     

竹红菌素金属配合物与人血清白蛋白相互作用的光谱研究(英文)

利用多种光谱方法研究了Mg~(2+)-HA,Y~(3+)-HA,La~(3+)-HA等竹红菌甲素金属离子配合物(M-HA)与人血清白蛋白(HSA)之间的相互作用.结果表明在pH 7.4和5.0条件下M-HA能够与HSA形成1:1的复合物,其结合常数均大于2×10~4L/mol.电子自旋共振和荧光猝灭实验表明HSA和M-HA在激发态条件下具有光诱导电子转移作用.     

Poly(methyl vinyl ether‐alt‐maleic anhydride) functionalized with 3‐aminophenylboronic acid: A new boronic acid polymer for sensing diols in neutral water

Amidation of poly(methyl vinyl ether‐alt‐maleic anhydride) with 3‐aminophenylboronic acid was used to prepare a new boronic acid polymer. The binding of catechol dye, Alizarin Red S to the polymer obtained resulted in getting a stable, colored sensor which was used to establish association constants with different diols in competitive assay. The binding of different diols was readily detected by color change and absorbance values measured at 450 nm were used to calculate the association constants. The polymer obtained formed high‐affinity complexes with ribonucleosides, particularly cytidine and uridine. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40778.     

A Minimalist Approach to the Design of Complexity‐Enriched Bioactive Small Molecules: Discovery of Phenanthrenoid Mimics as Antiproliferative Agents

Over the last decades, much effort has been devoted to the design of the “ideal” library for screening, the most promising strategies being those which draw inspiration from biogenic compounds, as the aim is to add biological relevance to such libraries. On the other hand, there is a growing understanding of the role that molecular complexity plays in the discovery of new bioactive small molecules. Nevertheless, the introduction of molecular complexity must be balanced with synthetic accessibility. In this work, we show that both concepts can be efficiently merged—in a minimalist way—by using very simple guidelines during the design process along with the application of multicomponent reactions as key steps in the synthetic process. Natural phenanthrenoids, a class of plant aromatic metabolites, served as inspiration for the synthesis of a library in which complexity‐enhancing features were introduced in few steps using multicomponent reactions. These resulting chemical entities were not only more complex than the parent natural products, but also interrogated an alternative region of the chemical space, which led to an outstanding hit rate in an antiproliferative assay: four out of twenty‐six compounds showed in vitro activity, one of them being more potent than the clinically useful drug 5‐fluorouracil.