Effective Iodine Capture Behavior by a Censer-shaped Macrocycle in Vapor Phase and Aqueous Solution

Iodine capture is of great significance for disposal of the hazardous radioactive iodine. CTX[P(O)Ph] , one kind of censer-shaped macrocycle cyclotrixylohydroquinoylene ( CTX ) derivatives, was applied as an efficient iodine adsorbent. It showed satisfactory iodine adsorption capacity in vapor phase and could be reused without obvious adsorption capacity loss. Besides, the adsorbent could also uptake iodine in water. Fortunately, two iodine loading CTX[P(O)Ph] crystal structures were obtained under different conditions to explore the mechanism of iodine adsorption. This work provides a relatively rare example of iodine adsorption by macrocycle. It is promising that the results with crystal information might be meaningful for exploring and designing new kinds of iodine adsorbents.     

Formation and Physicochemical Features of Hybrid Threadlike Micelles in Aqueous Solution

We investigate the construction of long, stable hybrid threadlike micelles consisting of polyelectrolytes and oppositely charged surfactants in aqueous solution and examine the physicochemical features such as their structure and viscoelastic behavior in aqueous solution. The most important point for their construction is the careful control of interactions, especially electrostatic interactions, caused between the surfactants and polyelectrolytes. Incorporated polyelectrolytes are fully extended in these hybrid threadlike micelles irrespective of the molecular weight of the polymer. The viscoelastic behavior of the hybrid threadlike micellar solution is similar to that of ordinary threadlike micellar systems consisting of low‐molecular‐weight substances. However, the inclusion of polymers in the micelles causes differences in their mechanical properties.     

Binding and Sensing Properties of a Hybrid Naphthalimide–Pyrene Aza-Cyclophane towards Nucleotides in an Aqueous Solution

Selective recognition of nucleotides with synthetic receptors is an emerging direction to solve a series of nucleic acid-related challenges in biochemistry. Towards this goal, a new aza-cyclophane with two different dyes, naphthalimide and pyrene, connected through a triamine linker has been synthesized and studied for the ability to bind and detect nucleoside triphosphates in an aqueous solution. The receptor shows Foerster resonance energy transfer (FRET) in fluorescence spectra upon excitation in DMSO, which is diminished dramatically in the presence of water. According to binding studies, the receptor has a preference to bind ATP (adenosine triphosphate) and CTP (cytidine triphosphate) with a “turn-on” fluorescence response. Two separate emission bands of dyes allow one to detect nucleotides in a ratiometric manner in a broad concentration range of 10⁻⁵–10⁻³ M. Spectroscopic measurements and quantum chemical calculations suggest the formation of receptor–nucleotide complexes, which are stabilized by dispersion interactions between a nucleobase and dyes, while hydrogen bonding interactions of nucleobases with the amine linkers are responsible for selectivity.     

Binding Selectivity of Macrocycle Ionophores in Ionic Liquids versus Aqueous Solution and Solvent‐free Conditions

The understanding of supramolecular recognition in room‐temperature ionic liquids (RTILs) is key to develop the full potential of these materials. In this work, we provide insights into the selectivity of the binding of alkali metal cations by standard cyclodextrin and calixarene macrocycles in RTILs. A direct laser desorption/ionization mass spectrometry approach is employed to determine the relative abundances of the inclusion complexes formed through competitive binding in RTIL solutions. The results are compared with the binding selectivities measured under solvent‐free conditions and in water/methanol solutions. Cyclodextrins and calixarenes in which the peripheral OH groups are substituted by bulkier side groups preferentially bind to Cs⁺. Such specific ionophoric behavior is substantially enhanced by solvation effects in the RTIL. This finding is rationalized with the aid of quantum mechanical calculations, in terms of the conformational features and steric interactions that drive the solvation of the inclusion complexes by the bulky RTIL counterions.     

卤键在化学传感和分子识别中的应用

卤键是一种新的分子间非共价作用力,它存在于卤素原子(路易斯酸)和具有孤电子对的原子或π-电子体系(路易斯碱)之间,在超分子化学、材料科学、生物识别和药物设计等领域已经显示出独特的优势。本文主要从卤键的特征和在化学传感和分子识别中的应用以及发展前景等几方面进行了介绍,期望引起人们对卤键的更多关注。     

Preparation and Function of Poly(acrylic acid)s Modified by Supramolecular Complex Composed of Porphinatoiron and a Cyclodextrin Dimer That Bind Diatomic Molecules (O2 and CO) in Aqueous Solution

Poly(acrylic acid) (PAA) is modified by 5‐(4‐β‐alanylaminophenyl)‐10,15,20‐tris(4‐sulfonatophenyl) porphinatoiron(III) to yield iron porphyrin‐bearing PAAs (FeP(n)s) through a condensation reaction. FeP(n)s were further functionalized by Py3CD, which is a per‐O‐methylated β‐cyclodextrin (CD) dimer with a pyridine linker and includes the porphyrin pendants to form ferric hemoCD‐P(n)s. Ferrous hemoCD‐P(3), having three porphyrin chromophores in a polymer chain, is shown to bind molecular oxygen (P_1/2=7.9±1.4 Torr) in aqueous solution at pH 7.0 and 25 °C, affording oxy‐hemoCD‐P(3). Oxy‐hemoCD‐P(3) is biphasically autoxidized to ferric hemoCD‐P(3), with 27 % of the dioxygen adducts being rapidly oxidized. The rate of autoxidation of oxy‐hemoCD‐P(15), having 15 porphyrin chromophores in a polymer chain, was much faster than that of oxy‐hemoCD‐P(3), thus suggesting self‐catalyzed autoxidation of oxy‐hemoCD‐P(n)s. Oxy‐hemoCD‐P(n)s are markedly stabilized by catalase, thereby indicating that hydrogen peroxide generated from oxy‐hemoCD‐P(n) accelerates the autoxidation. Most of the hemoCD‐P(3) molecules injected into the femoral vein of a rat remained in the body, though about 16 % of the hemoCD‐P(3) molecules were excreted in the urine as a carbon monoxide adduct.     

The Menshutkin Reaction in the Gas Phase and in Aqueous Solution: A Valence Bond Study

The recently developed (L. Song, W. Wu, Q. Zhang, S. Shaik, J. Phys. Chem. A 2004 , 108, 6017–6024) valence bond method coupled to a polarized continuum model (VBPCM) is applied to the Menshutkin reaction, NH₃+CH₃Cl→CH₃NH₃⁺+Cl^?, in the gas phase and in aqueous solution. The computed barriers and reaction energies at the level of the breathing orbital VB method (P. C. Hiberty, J. P. Flament, E. Noizet, Chem. Phys. Lett. 1992 , 189, 259), BOVB and VBPCM//BOVB, are comparable to CCSD(T) and CCSD(T)//PCM results and to experimental values in solution. The gas‐phase reaction is endothermic and leads to an ion‐pair complex via a late transition state. By contrast, the reaction in the aqueous phase is exothermic and leads to separate solvated ions as reaction products, via an early transition state. The VB calculations provide also the reactivity parameters needed to apply the valence bond state correlation diagram method, VBSCD (S. Shaik, A. Shurki, Angew. Chem. Int. Ed. 1999 , 38, 586). It is shown that the reactivity parameters along with their semiempirical derivations provide together a satisfactory qualitative and quantitative account of the barriers.     

Intramolecular Interactions of a Phenyl/Perfluorophenyl Pair in the Formation of Supramolecular Nanofibers and Hydrogels

A new system for the incorporation of a phenyl/perfluorophenyl pair in the structure of a peptide hydrogelator was developed. The strategy is based on the idea that the integration of an end‐capped perfluorophenyl group and a phenylalanine with a phenyl moiety in the side chain forms an intramolecular phenyl/perfluorophenyl pair, which can be used to promote the formation of the supramolecular nanofibers and hydrogels. This work illustrates the importance of structure‐hydrogelation relationship and provides new insights into the design of self‐assembly nanobiomaterials.     

Synthesis of Chiral Resorcinarene-based Hosts and a Mass Spectrometric Study of their Chemistry in Solution and the Gas Phase

The syntheses and characterization of new chiral tetrabenzoxazine and tetrakis-(dialkylaminomethyl) resorcinarenes can be achieved through the reaction of resorcinarene with chiral amines and formaldehyde. In order to examine their host–guest chemistry, chiral quaternary ammonium guests were synthesized by methylation of different amines and amino acid methyl esters through a reductive methylation followed by addition of methyl iodide. Subsequent anion exchange of the iodide against tetraphenylborate helps to improve solubility of the salts in organic solvents. After characterization in solution, mass spectrometry is used to examine the resorcinarenes’ chemistry in the gas phase. Interesting implications of the fragmentation behavior for their solution phase chemistry arise, for which a first example is presented. Ammonium ion binding is indicated by mass spectrometry. Nevertheless, chiral recognition between the chiral hosts and pseudoracemic 1:1 mixtures of appropriately deuterium-labeled chiral guest cations is however not observed.     

Dynamic Covalent Synthesis of Donor–Acceptor Interlocked Architectures in Solution and at the Solution:Surface Interface

Despite advances in the range of mechanically interlocked architectures that can be synthesized and operated as supramolecular machines, motors and sensors in solution, in many cases their synthesis is laborious and expensive requiring long multistep pathways with extensive purification at each stage. Dynamic covalent chemistry has been shown to overcome problems with traditional kinetically controlled synthetic approaches that often afford low yields of interlocked architectures due to irreversible formation of non‐interlocked by‐products. Herein, we describe the use of reversible disulfide exchange reactions as a means to assemble catenanes and rotaxanes in organic solutions. Moreover, the application of this thermodynamic approach to assemble interlocked architectures at the solution:surface interface, specifically polymer resins, is discussed.     

A Journey from Thermally Tunable Synthesis to Spectroscopy of Phenylmethanimine in Gas Phase and Solution

Phenylmethanimine is an aromatic imine with a twofold relevance in chemistry: organic synthesis and astrochemistry. To tackle both aspects, a multidisciplinary strategy has been exploited and a new, easily accessible synthetic approach to generate stable imine-intermediates in the gas phase and in solution has been introduced. The combination of this formation pathway, based on the thermal decomposition of hydrobenzamide, with a state-of-the-art computational characterization of phenylmethanimine laid the foundation for its first laboratory observation by means of rotational electric resonance spectroscopy. Both E and Z isomers have been accurately characterized, thus providing a reliable basis to guide future astronomical observations. A further characterization has been carried out by nuclear magnetic resonance spectroscopy, showing the feasibility of this synthetic approach in solution. The temperature dependence as well as possible mechanisms of the thermolysis process have been examined.     

Highly Sensitive and Selective Molecular Probes for Chromo-Fluorogenic Sensing of Carbon Monoxide in Air,Aqueous Solution and Cells

Optical sensing offers a low-cost and effective means to sense carbon monoxide in air and in solution. This contribution reports the synthesis of a new series of vinyl complexes [Ru(CH=CHR)Cl(CO)(TBTD)(PPh₃)₂] (R=aryl, TBTD=5-(3-thienyl)-2,1,3-benzothiadiazole) and shows them to be highly sensitive and selective probes for carbon monoxide in both solution and air. Depending on the vinyl substituent, chromogenic and fluorogenic responses signalled the presence of this invisible, odourless, tasteless and toxic gas. Adsorbing the complexes on silica produced colorimetric probes for the ′naked eye′ detection of CO in the gas phase with a limit of detection as low as 8 ppm in some cases, while the release of the TBTD fluorophore allowed detection at much lower concentrations through the fluorescence response. Structural data were obtained by single-crystal X-ray diffraction techniques, while the photophysical behaviour was explored computationally using TD-DFT experiments. The systems were also shown to be selective for CO over all other gases tested, including water vapour and common organic solvents. By introducing a poly(ethylene)glycol chain to the vinyl functionality, water compatibility was achieved and these non-cytotoxic complexes were employed in the sensing of CO in HeLa cells, offering a simple and rapid system for sensing this gasotransmitter in this challenging medium.     

Halogen‐Bonded Supramolecular Capsules in the Solid State,in Solution,and in the Gas Phase

Supramolecular capsules were assembled by neutral halogen bonding (XB) and studied in the solid state, in solution, and in the gas phase. The geometry of the highly organized capsules is shown by an X‐ray crystal structure which features the assembly of two XB hemispheres, geometrically rigidified by H‐bonding to eight MeOH molecules and encapsulation of two benzene guests. To enhance capsular association strength, tuning the XB donor is more efficient than tuning the XB acceptor, due to desolvation penalties in protic solvents, as shown for a tetraquinuclidine XB acceptor hemisphere. With a tetra(iodoethynyl) XB donor and a tetralutidine XB acceptor, the association in deuterated benzene/acetone/methanol 70:30:1 at 283 K reaches K _a=(2.11±0.39)×10⁵ m ⁻¹ (ΔG =−6.9±0.1 kcal mol⁻¹). The stability of the XB capsules in the gas phase was confirmed by electrospray ionization mass spectrometry (ESI‐MS). A new guest binding site was uncovered within the elongated iodoethynyl capsule.     

Highly Enhanced Fluorescence of Supramolecular Polymers Based on a Cyanostilbene Derivative and Cucurbit[8]uril in Aqueous Solution

Supramolecular polymers (SPs) have received great attention because of their potential for various practical applications. As part of our search for SPs that are highly fluorescent in aqueous media, we designed a system based on a cucurbit[8]uril (CB[8]) host and a newly designed cyanostilbene guest. Fluorescence quantum yields of ≈0 % in the disassembled monomer state and 91 % in the CB[8]‐induced SP state were obtained. The intriguing photophysical properties of the SP are elucidated through detailed experimental and computational analysis, paving the way towards a fascinating class of water‐soluble fluorescent SPs.     

Aqueous Phase Sensing of Fe3+ and Ascorbic Acid by a Metal–Organic Framework and Its Implication in the Construction of Multiple Logic Gates

A new Hf^IV‐based metal‐organic framework with UiO‐66 topology was synthesized via a one‐step solvothermal method by using 3‐methyl‐4‐phenylthieno[2,3‐b]thiophene‐2,5‐dicarboxylic acid (H₂MPTDC) as a ligand. The MOF material showed a high stability in a broad pH range (from pH 2 to pH 12) in an aqueous medium. The presence of hydrophobic methyl and phenyl substituents in the carboxylic acid ligand and strong Hf?O bond play crucial roles in its stability. The new MOF material was systematically characterized by various techniques such as XRPD, N₂ sorption, thermogravimetric analyses and FT‐IR spectroscopy. The photophysical properties of the MOF material were also examined by steady‐state and time‐resolved fluorescence studies. It was observed that the blue fluorescence of the MOF material was selectively quenched in the presence of Fe³⁺ ion in pure aqueous medium. A mechanistic study disclosed that quenching occurs via a strong inner filter effect (IFE) arising from Fe³⁺ ion in aqueous medium. Interestingly, the fluorescence of the MOF material can be recovered by elimination of the IFE of Fe³⁺ ion via reduction of Fe³⁺ ion by ascorbic acid (AA). Based on the fluorescence recovery by AA, a MOF based on‐off‐on probe was developed for the sensing of Fe³⁺ ion and AA in aqueous medium. Inspired by this reversible sensing event, we demonstrate basic (NOT, OR, YES, INHIBIT and IMP) and higher integrated logic operations utilizing this fluorescent MOF. This MOF‐based logic systems could be potentially used for next‐generation logic‐gate based analytical applications as well as for the detection and discrimination of targeted molecules in various complex domains.     

Helicity Control in the Aggregation of Achiral Squaraine Dyes in Solution and Thin Films

Squaraine dyes are well known for their strong absorption in the visible regime. Reports on chiral squaraine dyes are, however, scarce. To address this gap, we here report two novel chiral squaraine dyes and their achiral counterparts. The presented dyes are aggregated in solution and in thin films. A detailed chiroptical study shows that thin films formed by co-assembling the chiral dye with its achiral counterpart exhibit exceptional photophysical properties. The circular dichroism (CD) of the co-assembled structures reaches a maximum when just 25 % of the chiral dye are present in the mixture. The solid structures with the highest relative CD effect are achieved when the chiral dye is used solely as a director, rather than the structural component. The chiroptical data are further supported by selected spin-filtering measurements using mc-AFM. These findings provide a promising platform for investigating the relationship between the dissymmetry of a supramolecular structure and emerging material properties rather than a comparison between a chiral molecular structure and an achiral counterpart.     

Supramolecular Complexation of N‐Alkyl‐ and N,N′‐Dialkylpiperazines with Cucurbit[6]uril in Aqueous Solution and in the Solid State

Water seeds : Complex stoichiometry/composition and degree of oligomerization (oligomeric supramolecular complex formation) of cucurbit[6]uril (CB[6]) with N‐alkyl‐ and N,N′‐dialkylpiperazine were investigated in aqueous solutions by means of isothermal titration calorimetry (ITC), ESI‐MS, NMR and light scattering measurements.

     

Criegee中间体气相反应热力学的G2理论计算

Criegee中间体已被认为是大气中一些重要污染物的来源，是引发大量次级反应的关键物质，与光化学氧化剂、有机过氧化物的产生，以及与酸雨、大气光化学烟雾和森林衰退等许多环境问题有关[1-4]．但由于Criegee中间体寿命短，对其可能参与的一些大气化学反应进行实验研究有一定难