Small molecule matrix-assisted laser desorption/ionization time-of-flight mass spectrometry using a polymer matrix

We have employed a light-absorbing electrically conductive polymer as a matrix to determine the molecular mass of small organic molecules using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. This method, which is in contrast to the usual MALDI strategy for matrix selection in which a small molecule matrix is used with a high molecular mass analyte, addresses the problem of matrix interference which limits the usefulness of MALDI-TOF for small molecule analysis. Use of negative ion mode offers advantages for this application. Using this approach, we have obtained clean molecular ion mass spectra of small organic molecules in the mass range 100-300 Da.     

介孔球状纳米羟基磷灰石的多级组装合成

利用支撑液膜控制离子在隔离的两相中流动传输, 同时添加有机小分子协同液膜界面形成模板, 诱导纳米晶体进行嵌段组合团聚成非致密型超结构, 得到一种由纳米片状亚单元卷曲后组装形成的新型介孔球状纳米羟基磷灰石材料. TEM, XRD, BET等结果表明, 产物纳米羟基磷灰石平均孔径为17.5 nm. 细胞毒性实验表明, 不同浓度的细胞存活率高于80%, 细胞毒性为1级, 可认为材料具有良好的细胞相容性. FT-IR, UV光谱结果表明产物能有效的对鬼臼毒素进行载药包裹, 平均载药量为12.9%, 包封率为65.5%. 这种新型介孔超结构HA在酶、蛋白质的固定和分离、药物转染等方面具有其潜在的应用价值.     

A–π–D–π–A Electron‐Donating Small Molecules for Solution‐Processed Organic Solar Cells: A Review

Organic solar cells based on semiconducting polymers and small molecules have attracted considerable attention in the last two decades. Moreover, the power conversion efficiencies for solution‐processed solar cells containing A–π–D–π–A‐type small molecules and fullerenes have reached 11%. However, the method for designing high‐performance, photovoltaic small molecules still remains unclear. In this review, recent studies on A–π–D–π–A electron‐donating small molecules for organic solar cells are introduced. Moreover, the relationships between molecular properties and device performances are summarized, from which inspiration for the future design of high performance organic solar cells may be obtained.     

Regioselective Cyclotrimerization of Terminal Alkynes Using a Digermyne

The catalytic activation of small neutral molecules followed by the formation of C?C bonds is a highly important method to increase the complexity and/or value of simple starting materials. Reported is an isolable digermyne, a compound with a Ge≡Ge bond, which acts as a precatalyst for the cyclotrimerization of terminal arylacetylenes to afford the corresponding 1,2,4‐triarylbenzenes with absolute regioselectivity. The results demonstrate that bespoke main‐group‐element compounds can catalytically activate and transform small neutral organic molecules and induce the formation of C?C bonds.     

线型碳的化学法合成研究进展

线型碳是碳的一种新的同素异形体,可望应用于生物医学和材料科学。线型碳的合成方法主要包括物理法和化学法。近年来,基于利用有机小分子或各种聚合物为原料的化学合成法发展迅速,本文主要综述其研究新进展。     

外缘烷基链长对共轭有机小分子聚集行为及光电性质影响

改变分子化学结构和调控分子结构聚集态行为从而影响或改变材料的化学和物理性质, 是开发新型高效有机光电功能材料的重要手段. 在共轭有机分子外缘引入烷基链一般是为了改进材料溶解性能, 但近来的一些研究表明, 烷基链长对一些共轭有机小分子固态聚集行为和光电性质具有重要影响, 烷基链扮演着显著调控材料光电性质的“功能基团”作用. 本文以聚集诱导发光（aggregation-induced emission, AIE）/聚集强化荧光（aggregation enhanced emission, AEE）发射共轭有机小分子为重点, 对近年来有关烷基链长对共轭有机分子聚集形态和光电性质影响的一些典型事例进行评述, 旨在使人们在进行共轭有机分子设计合成及其结构与性能关系研究中能够关注烷基链的因素, 使烷基链变化作为功能导向晶态共轭有机材料设计合成及其可控制备的一种手段.     

Study of molecular interactions between lipids and proteins using dynamic surface tension measurements: a review

Molecular interactions between small molecules and proteins, such as binding of lipids to proteins, are of fundamental importance in various biological processes. A recently-developed method based on dynamic surface tension measurement is efficient and versatile in detecting such molecular interactions: Axisymmetric Drop Shape Analysis (ADSA) provides a tool for measuring the surface tension (γ) response to surface area changes. Through the analysis of the γ response pattern, surface competitive adsorption between small organic molecules and protein molecules can be detected. Surface squeeze-out of small molecules by proteins can also be observed. Molecular binding of lipids to proteins manifests itself in a modification of the γ response which is not compatible with a simple superposition of the two individual patterns. The specific binding can be studied in terms of dose effects and specificity.     

Au@SiO2 core-shell nanoparticles for laser desorption/ionization time of flight mass spectrometry

In matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), the analysis capability, especially for small molecules, is often compromised by the addition of organic matrices due to the existence of background signals. Herein we report a new detection method on the utility of core-shell nanoparticles (CSNPs) as energy transfer structure in LDI-TOF-MS. The LDI-TOF-MS based on gold-silica core-shell nanoparticles with ultrathin silica shell of 2-4 nm (Au@utSiO(2) CSNPs) was effectively applied to the analysis of many compounds, especially for small functional molecules and polymers, which was more promising than MALDI-TOF-MS.     

Assignment of the molecular absolute configuration through the ab initio Hartree-Fock calculation of the optical rotation: can the circular dichroism data help in reducing basis set requirements?

In this paper the calculation of the optical rotation (OR) of some rigid organic molecules, using the Hartree-Fock method with small (6-31G, DZP) basis sets, has been studied thoroughly to carefully evaluate the scope and limitations of this method, previously introduced by other authors. Calculations on test molecules (compounds 1-13) together with a careful analysis of their CD spectra allow a simple criterion for the reliability of this approach to be formulated: for unsaturated and/or aromatic (i.e., absorbing in the near-UV region) molecules, if the [alpha](D) is quantitatively determined by the lowest energy Cotton effect (at wavelengths >220 nm), then the HF/6-31G result is reliable. The usefulness of this method for the experimental organic chemist has been further demonstrated because the OR (sign and order of magnitude) of compounds 14-19 (i.e., large molecules having considerable interest in organic chemistry), which fulfill the above criterion and for which an extended basis set treatment is not feasible owing to their size, is correctly predicted.     

A Biocompatible Alkene Hydrogenation Merges Organic Synthesis with Microbial Metabolism

Organic chemists and metabolic engineers use orthogonal technologies to construct essential small molecules such as pharmaceuticals and commodity chemicals. While chemists have leveraged the unique capabilities of biological catalysts for small‐molecule production, metabolic engineers have not likewise integrated reactions from organic synthesis with the metabolism of living organisms. Reported herein is a method for alkene hydrogenation which utilizes a palladium catalyst and hydrogen gas generated directly by a living microorganism. This biocompatible transformation, which requires both catalyst and microbe, and can be used on a preparative scale, represents a new strategy for chemical synthesis that combines organic chemistry and metabolic engineering.     

可溶液加工的D-A-D型有机小分子的烷基链效应及光电性能

设计合成了3种可溶液加工的基于噻吩给体和2-吡喃-4-亚基丙二氰(PM)受体的新型Donor-Acceptor-Donor(D-A-D)型有机小分子TPT-N, TPT-S和TPT-D. 研究了噻吩给体单元上烷基链的数目对分子的溶解性、 光物理(吸收特性)、 热稳定和光电性能的影响. 结果表明, 随着烷基链的增加, 分子的溶解性增加, 成膜性能提高; 分子在溶液中的吸收光谱发生红移, 薄膜的吸收谱带变窄, 分子的最高占有分子轨道(HOMO)能级提高. 以D-A-D型有机小分子为给体, 富勒烯C₆₀衍生物-苯基-C₆₁-丁酸甲酯(PCBM)为受体制备了结构为ITO/PEDOT∶PSS/D-A-D∶PCBM/LiF/Al的体异质结太阳能电池. 研究结果表明, 基于单烷基链的TPT-S的太阳能电池具有相对较高的能量转换效率. 说明在D-A-D型有机小分子太阳能电池材料中, 烷基链的数目是决定材料性能及器件性能的重要因素之一.     

Crossing borders to bind proteins—a new concept in protein recognition based on the conjugation of small organic molecules or short peptides to polypeptides from a designed set

A new concept for protein recognition and binding is highlighted. The conjugation of small organic molecules or short peptides to polypeptides from a designed set provides binder molecules that bind proteins with high affinities, and with selectivities that are equal to those of antibodies. The small organic molecules or peptides need to bind the protein targets but only with modest affinities and selectivities, because conjugation to the polypeptides results in molecules with dramatically improved binder performance. The polypeptides are selected from a set of only sixteen sequences designed to bind, in principle, any protein. The small number of polypeptides used to prepare high-affinity binders contrasts sharply with the huge libraries used in binder technologies based on selection or immunization. Also, unlike antibodies and engineered proteins, the polypeptides have unordered three-dimensional structures and adapt to the proteins to which they bind. Binder molecules for the C-reactive protein, human carbonic anhydrase II, acetylcholine esterase, thymidine kinase 1, phosphorylated proteins, the D-dimer, and a number of antibodies are used as examples to demonstrate that affinities are achieved that are higher than those of the small molecules or peptides by as much as four orders of magnitude. Evaluation by pull-down experiments and ELISA-based tests in human serum show selectivities to be equal to those of antibodies. Small organic molecules and peptides are readily available from pools of endogenous ligands, enzyme substrates, inhibitors or products, from screened small molecule libraries, from phage display, and from mRNA display. The technology is an alternative to established binder concepts for applications in drug development, diagnostics, medical imaging, and protein separation.     

Small organic molecular imprinted materials: their preparation and application

Molecular imprinting is a technique for preparing polymeric materials that are capable of recognizing and binding the desired molecular target with a high affinity and selectivity. The materials can be applied to a wide range of target molecules, even those for which no natural binder exists or whose antibodies are difficult to raise. The imprinting of small organic molecules (e.g., pharmaceuticals, pesticides, amino acids, steroids, and sugars) is now almost routine. In this review, we pay special attention to the synthesis and application of molecular imprinted polymer (MIPs) imprinted with small organic molecules, including herbicides, pesticides, and drugs. The advantages, applications, and recent developments in small organic molecular imprinted technology are highlighted.     

木质生物质转化高附加值化学品

本文阐述了木质生物质转化为主要化学品的类型及其转化途径,提出了从木质生物质转化高附加值化学品的新思路.木质生物质通过一定的降解或分解途径,可产生很多有重要价值的有机小分子化合物,这些有机小分子化合物有葡萄糖、木糖、苯丙烷单体及二聚体,气态小分子如CH4和CO,液态小分子如有机酸、醛、醇,重要基础平台化合物糠醛、乙酰丙酸、木糖醇、乙醇等.通过这些小分子有机化合物的转化,可产生替代石油基产品的高附加值化学品,对可持续发展具有重要意义.     

Automatic perception of organic molecules based on essential structural information

Format conversion is very common in structure preparation in molecular modeling studies. Unfortunately, format conversion cannot always be executed precisely. We have developed an automatic method, called I-interpret (available on-line at http://www.sioc-ccbg.ac.cn/software/I-interpret/), for interpreting the chemical structure of a given organic molecule merely from its essential structural information, including element identities and three-dimensional coordinates of its component atoms. I-interpret uses standard geometrical parameters of organic molecules in atom/bond-type assignment. A series of elaborate considerations are arranged in a logical sequence for this purpose. I-interpret was tested on a set of 179 small organic molecules from the Protein Data Bank and a set of 1990 organic molecules from the NCI diversity set. On both sets, it achieved a success rate of over 95% in interpreting the correct chemical structures, outperforming other programs under our evaluation. I-interpret also provides users some optional functions, which makes it more flexible and powerful in practice. It may serve as a valuable tool for processing chemical structures in molecular modeling.     

有机小分子纳米粒子的光学诊疗应用

癌症严重威胁着人类健康, 因此, 急需开发高效的诊断和治疗方法. 基于光敏剂和近红外激光的光学诊疗将诊断和治疗集于一体, 与传统的手术治疗和化学治疗相比, 光学诊疗显示出无创性和高空间选择性的优点. 有机小分子染料具有确定且易于修饰的化学结构、 良好的重现性和优异的生物相容性, 与无机和聚合物材料相比, 它是一类具有前景的可用于光学诊疗的光敏剂. 本文总结了基于传统小分子染料、 给体-受体(D-A)共轭小分子和聚集诱导发光(AIE)分子等有机小分子的纳米粒子在光学诊疗中的应用. 此外, 对于光学诊疗用有机小分子染料纳米粒子未来的挑战和前景也进行了展望.     

木质生物质转化高附加值化学品

本文阐述了木质生物质转化为主要化学品的类型及其转化途径,提出了从木质生物质转化高附加值化学品的新思路。木质生物质通过一定的降解或分解途径,可产生很多有重要价值的有机小分子化合物,这些有机小分子化合物有葡萄糖、木糖、苯丙烷单体及二聚体,气态小分子如CH4和CO,液态小分子如有机酸、醛、醇,重要基础平台化合物糠醛、乙酰丙酸、木糖醇、乙醇等。通过这些小分子有机化合物的转化,可产生替代石油基产品的高附加值化学品,对可持续发展具有重要意义。     

Orientational properties of stretched polystyrene gels in organic solvents and the suppression of their residual 1H NMR signals

While residual dipolar couplings (RDCs) are an established method in high-resolution biomolecular NMR, their use for structure determination of small molecules in organic solvents is limited by the alignment media available. Only recently stretched polystyrene (PS) gels were introduced for the measurement of RDCs on small compounds that allowed urgently needed free scalability of the induced anisotropy. Here, the properties of such stretched PS gels in different organic solvents as well as for different magnetic field strengths and temperatures are studied and practical NMR-spectroscopic aspects are discussed.     

The Search for Highly Colored Organic Compounds

Until now the study of organic compounds in which the π-electron system is excited by absorbed light has been mainly concentrated on the ultraviolet and visible regions of the electromagnetic spectrum. Various new applications, such as the use of conjugated organic compounds as dye lasers or as materitals for storing information with the help of diode lasers, led to the synthesis of new compounds which absorb light in the near in infrared (NIR). It is possible to use structure-color relationships to predict the properties of such new compounds when they belong to dyestuff classes which have already been studied in detail; in this case the approach involves decreasing the energy difference between the ground state and the first excited state. A less conventional starting point is provided by molecular structures in which from the outset there is only a very small energy difference between the lowest-energy electronic states; such diradicaloid molecules occupy a special position among the various types of organic compounds. It is possible by means of suitable structural modification to stabilize such molecules in a singlet from which absorbs light at very long wavelengths (i.e. at small wave numbers).     

Liquid Metastable Precursors of Ibuprofen as Aqueous Nucleation Intermediates

The nucleation mechanism of crystals of small organic molecules, postulated based on computer simulations, still lacks experimental evidence. In this study we designed an experimental approach to monitor the early stages of the crystallization of ibuprofen as a model system for small organic molecules. Ibuprofen undergoes liquid–liquid phase separation prior to nucleation. The binodal and spinodal limits of the corresponding liquid–liquid miscibility gap were analyzed and confirmed. An increase in viscosity sustains the kinetic stability of the dense liquid intermediate. Since the distances between ibuprofen molecules within the dense liquid phase are similar to those in the crystal forms, this dense liquid phase is identified as a precursor phase in the nucleation of ibuprofen, in which densification is followed by generation of structural order. This discovery may make it possible to enrich poorly soluble pharmaceuticals beyond classical solubility limitations in aqueous environments.