非富勒烯类有机小分子受体材料

富勒烯及其衍生物因具有多维电荷传输特性和与给体材料形成独特的相分离结构等特点,在有机光伏领域占据主导地位。然而,富勒烯类受体材料本身也有一些难以克服的缺点,如可见光范围内吸收能力弱、修饰困难、成本高等,进而限制了器件性能的提高和规模化使用。非富勒烯类小分子受体材料的研究引起越来越多的重视。研究者可借助丰富的化学手段,设计合成出具有特定聚集态形貌和优异性能的有机小分子及其寡聚物。本文总结了近几年关于苝四甲酰二亚胺类、吡咯并吡咯二酮类、苯并噻二唑类等几类性能相对优异的非富勒烯类有机小分子受体材料的最新研究进展,从分子结构上对其性能进行了剖析,对高性能受体材料的设计合成具有一定的指导意义。最后,讨论了提高非富勒烯类有机小分子受体材料器件性能的主要因素及其研究前景。     

Oriented Crystallization on Organic Monolayers to Control Concomitant Polymorphism

Nucleation events and crystal growth can be guided by molecular recognition at interfaces through intermolecular interactions. The short-acting antimicrobial sulfa drug sulfathiazole is known for its concomitant crystallization, which has five known polymorphs, due to conformational flexibility and hydrogen-bond synthon variation. In its development stage of a drug the issue of concomitant crystallization needs to be addressed with respect to patent litigation, including legal actions to protect patents against infringement. A functional self-assembled monolayer (SAM) of organic thiol on a gold surface has been employed as an efficient approach to control concomitant nucleation of such flexible drugs. The crystallization on a SAM surface is mostly kinetically driven and often leads to the nucleation of novel metastable forms. Spectroscopic, thermal analysis and X-ray diffraction studies reveal that a previously unknown, sixth form of the drug nucleates on the designed SAM surface.     

Light Harvesting and Amplification of Emission of Donor Perylene–Acceptor Perylene Aggregates in Aqueous Medium

With the aid of rational design, we have synthesized a pair of water‐soluble donor‐ and acceptor‐type twisted perylene bisimide units, which together form aggregates upon lowering the pH of the medium, providing bright yellow fluorescence. The light‐harvesting efficiency of the co‐assembled system can be tuned by controlling the ratio of donor to acceptor and 98.1 % efficiency has been achieved.     

Kinetics of Lysozyme Crystallization From Solution

Abstract

We suggest that the growth of molecular aggregates is the rate-controlling step in the crystallization of lysozyme from pH buffered aqueous solutions of strong electrolytes. We propose that the aggregation reaction passes through a charged transition state whose rate of formation is accelerated by Debye-Huckel screening and whose charge is stabilized by ion exchange with the solution. Applying the theory of the “primary kinetic salt effect”, we predict that the half-life for decay of the lysozyme concentration in solution in contact with a growing crystal should decrease linearly with the square root of the ionic strength. This prediction is confirmed experimentally in the case of lysozyme crystals precipitating at 4°C from pH buffered aqueous solutions of sodium chloride.     

Electronic Interactions of n‐Doped Perylene Diimide Groups Appended to Polynorbornene Chains: Implications for Electron Transport in Organic Electronics

A polymer consisting of a polynorbornene backbone with perylene diimide (PDI) pendant groups on each monomeric unit is synthesized via ring opening metathesis polymerization. The PDI pendant groups along the polymer backbone, studied by UV–vis absorption, fluorescence emission, and electron paramagnetic resonance spectroscopy in addition to electrochemical methods, show evidence of molecular aggregation and corresponding electronic coupling with neighboring groups, which forms pathways for efficient electron transport from one group to another in a specific reduced form. When n‐doped, the title polymer shows redox conductivity of 5.4 × 10⁻³ S cm⁻¹, comparable with crystalline PDI materials, and is therefore a promising material for use in organic electronics.     

Hydrophobicity Control in Adaptive Crystalline Assemblies

An amphiphile based on polyethylene glycol (PEG) polymer and two molecular moieties (perylene diimide and C₇ fluoroalkyl, PDI and C₇F) attached to its termini assembles into crystalline films with long‐range order. The films reversibly switch from crystalline to amorphous above the PEG melting temperature. The adaptive behavior stems from the responsiveness of the PEG domain and the robustness of the PDI and C₇F assemblies. The hydrophobicity of the film can be controlled by heating, resulting in switching from highly hydrophobic to superhydrophilic. The long‐range order, reversible crystallinity switching, and the temperature‐controlled wettability demonstrate the potential of block copolymer analogues based on simple polymeric/molecular hybrids.     

Crystalline Conjugated Polymers for Organic Solar Cells: From Donor,Acceptor to Single‐Component

Organic solar cells have made rapid progress in the last two decades due to the innovation of conjugated materials and photovoltaic devices. Microphase separation that connects with materials and devices plays a crucial role in the charge generation process. In this account, we summary our recent works of developing new crystalline conjugated polymers to control the microphase separation in thin films in order to realize high performance in solar cells, including crystalline diketopyrrolopyrrole‐based donor polymers, perylene bisimide‐based electron acceptors, and “double‐cable” conjugated polymers that contain covalently‐linked crystalline donor and acceptor in one material for single‐component organic solar cells.     

谷氨酸钠从其水溶液中的周期结晶现象

早在本世纪初物理化学家们就已观察到，某些物质从其熔融态或溶液中结晶出来时，在某些条件下可形成周期性的宏观结晶条纹［1，2］，这就是周期结晶现象，由于这种现象和晶体生长、材料物性以及成矿过程等重要问题紧密相关，很早就引起了人们的重视．近年来有关非平衡非线性系统中自发产生各种时空有序现象（自组织现象）的各种理论（如耗散结构理论）［3］的兴起，重新引起了人们对这类现象的兴趣．八十年代，Iwamoto等先后报道了甲基苄基氨基甲酸酯（MethylMesitylcarbamate）从氯仿溶液［4］和抗坏血酸（AscorbicAcid）从甲醇溶液［5］…     

Crystallization Force—A Density Functional Theory Concept for Revealing Intermolecular Interactions and Molecular Packing in Organic Crystals

Organic molecules are prone to polymorphic formation in the solid state due to the rich diversity of functional groups that results in comparable intermolecular interactions, which can be greatly affected by the selection of solvent and other crystallization conditions. Intermolecular interactions are typically weak forces, such as van der Waals and stronger short‐range ones including hydrogen bonding, that are believed to determine the packing of organic molecules during the crystal‐growth process. A different packing of the same molecules leads to the formation of a new crystal structure. To disclose the underlying causes that drive the molecule to have various packing motifs in the solid state, an electronic concept or function within the framework of conceptual density functional theory has been developed, namely, crystallization force. The concept aims to describe the local change in electronic structure as a result of the self‐assembly process of crystallization and may likely quantify the locality of intermolecular interactions that directs the molecular packing in a crystal. To assess the applicability of the concept, 5‐methyl‐2‐[(2‐nitrophenyl)amino]‐3‐thiophenecarbonitrile, so‐called ROY, which is known to have the largest number of solved polymorphs, has been examined. Electronic calculations were conducted on the seven available crystal structures as well as on the single molecule. The electronic structures were analyzed and crystallization force values were obtained. The results indicate that the crystallization forces are able to reveal intermolecular interactions in the crystals, in particular, the close contacts that are formed between molecules. Strong correlations exist between the total crystallization force and lattice energy of a crystal structure, further suggesting the underlying connection between the crystallization force and molecular packing.     

溶液间歇结晶动力学模型的新型算法

针对溶液间歇结晶过程, 基于粒数衡算理论和ΔL定律, 借助分段归纳的研究方法, 建立了晶体粒度分布函数各阶矩量的关联式. 利用此关联式, 对文献模型中晶体粒度分布函数的二阶矩量进行替换, 并结合计算机程序设计, 可直接拟合得到结晶体系的成核和生长动力学参数, 从而为结晶动力学模型的求解建立了一种新型算法. 通过对文献报道的硝酸钾水溶液和混二甲苯溶液两组结晶数据的模拟计算, 结果发现, 运用该算法求取的结晶成核和生长动力学参数均与传统的矩量变换法的计算结果相近, 但新建算法无需预知结晶体系的总传热系数.     

Enthalpy of Solution of Terfenadine in Different Solvents

Enthalpies of solution of various terfenadine samples in methanol and in ethanol were measured. Samples were prepared by crystallization in different solvents. The calorimetric results give important information on crystal structure of the terfenadine forms and on the solute/solvent interactions of this compound with the solvents.This revised version was published online in November 2005 with corrections to the Cover Date.     

Solution Crystallization Analysis by Laser Light Scattering (SCALLS)

Summary: Solution crystallization analysis by laser light scattering offers a direct way of studying the solution crystallization of polyolefins. The technique yields similar results to Crystaf, but in a shorter time and with apparently greater sensitivity in some cases. The use of SCALLS is demonstrated for the study of selected propylene/higher α-olefin copolymers. Some conclusions are also drawn regarding the effect of molecular weight on the solution crystallization of polyolefins.     

Collapse Transition‐Assisted Crystallization in P3HT Solution

Understanding the multiple phase transitions such as collapse transition, phase separation, and crystallization in solutions is of fundamental importance to control the solution structure of conjugated polymers in device processing. Combining in situ synchrotron radiation small and wide‐angle X‐ray scattering, ultrasensitive differential scanning calorimetry, ultraviolet–visible absorption spectroscopy, and polarized optical microscopy, we investigate the order–disorder transitions in poly(3‐hexylthiophene)/toluene solutions during cooling and heating processes. We demonstrate the occurrence of collapse transition of polymer chains from a random coil state to a lower dimensional network prior to the onset of crystallization during cooling in solution. This conformational preordering can lead to the formation of a lyotropic liquid crystalline phase, which is of great significance to the crystallization and ordering in polymer films, and further to promote its electric performance. It is examined that the mobility of films cast from chain‐collapsed solutions can be one order of magnitude higher than that from isotropic solutions with random‐coiled conformations. Thus, the conformational preordering in solutions is proposed to be a more efficient way than the postannealing of films to improve the electric performance of conjugated polymer films. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1105–1114     

Crystallization of poly(butylene adipate) in the presence of nucleating agents

The effect of nucleating agents on the polymorphic crystallization behavior of poly(butylene adipate) (PBA) was studied with four kinds of commercially available nucleating agents, such as talc and boron nitride. The crystal structures of the α and β forms were studied with wide‐angle X‐ray diffraction. The β‐to‐α‐crystal transformation of PBA in the absence and presence of the nucleating agents in isothermal crystallization and nonisothermal crystallization processes was studied with differential scanning calorimetry and polarized optical microscopy. In both isothermal and nonisothermal crystallization, the introduction of nucleating agents selectively initiated the nucleation of the α‐form crystal, which was relatively slow in the absence of nucleating agents. The nucleating activity of the four kinds of nucleating agents in the crystallization of the PBA α‐form crystal was determined by the study of the nonisothermal crystallization, spherulite morphology, and isothermal kinetics. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2340–2351, 2005     

Organic Matrix Assisted Low-temperature Crystallization of Black Phase Inorganic Perovskites

All-inorganic perovskites have attracted increasing attention for applications in perovskite solar cells (PSCs) and optoelectronics, including light-emitting devices (LEDs). Cesium lead halide perovskites with tunable I/Br ratios and a band gap aligning with the sunlight region are promising candidates for PSCs. Although impressive progress has been made to improve device efficiency from the initial 2.9 % with low phase stability to over 20 % with high stability, there are still questions regarding the perovskite crystal growth mechanism, especially at low temperatures. In this Minireview, we summarize recent developments in using an organic matrix, including the addition and use of organic ions, polymers, and solvent molecules, for the crystallization of black phase inorganic perovskites at temperatures lower than the phase transition point. We also discuss possible mechanisms for this low-temperature crystallization and their effect on the stability of black phase perovskites. We conclude with an outlook and perspective for further fabrication of large-scale inorganic perovskites for optoelectronic applications.     

New Developments in Crystallization Processing

The intention of this work presented is to introduce new processing principles for the crystallization of watery or fatty phases in food systems, and in particular to quantify the process — microstructure — product quality relationships for such food systems. The crystallization processes demonstrated in detail are high shear crystallization (i), spray crystallization (ii) and spray powder based seed crystallization (iii). Crystalline, semi-crystalline and/or amorphous structures were analysed by calorimetric, mechanical/rheological and microscopical methods. Quality aspects of the final food products, which are related to the structure of the crystalline and/or amorphous components, were investigated additionally.This revised version was published online in November 2005 with corrections to the Cover Date.     

Molecular assemblies of perylene bisimide dyes in water

Perylene bisimides are among the most valuable functional dyes and have numerous potential applications. As a result of their chemical robustness, photostability, and outstanding optical and electronic properties, these dyes have been applied as pigments, fluorescence sensors, and n‐semiconductors in organic electronics and photovoltaics. Moreover, the extended quadrupolar π system of this class of dyes has facilitated the construction of numerous supramolecular architectures with fascinating photophysical properties. However, the supramolecular approach to the formation of perylene bisimide aggregates has been restricted mostly to organic media. Pleasingly, considerable progress has been made in the last few years in developing water‐soluble perylene bisimides and their application in aqueous media. This Review provides an up‐to‐date overview on the self‐assembly of perylene bisimides through π–π interactions in aqueous media. Synthetic strategies for the preparation of water‐soluble perylene bisimides and the influence of water on the π–π stacking of perylene bisimides as well as the resulting applications are discussed.     

Control over Kinetic and Thermodynamically Driven Pathways of Crystallization to Yield Cofacial and Slipped-Stack Dimers in Single Crystals

Control over the molecular packing in the solid state is of utmost importance in regulating the bulk optical properties of organic semiconductors. The electronic coupling between the molecules makes it possible to improve the properties of the bulk materials. This work reports an example of control over the selective formation of polymorphic single crystals of donor–acceptor-type small-molecule compound 25TR by 1) kinetic or 2) thermodynamic course of crystallisation to yield slipped stack (S) and cofacial (C) dimers in the single crystals. The distinct optical characteristics of the C-dimer and S-dimer are summarised. Both forms show significant excitonic interactions in the solid state, and the S-dimeric form has strong yellowish orange fluorescence, whereas the C-dimeric form is non-fluorescent in the crystalline state. DFT calculations and differential scanning calorimetric experiments revealed that the C-dimer polymorph is the thermodynamically stable form with a free energy offset of 0.43 eV in comparison with the S-dimer. Interestingly, the thermodynamically driven non-fluorescent single crystal was found to be convertible to its fluorescent form irreversibly by thermal trigger. The charge-carrier-transport characteristics of these two polymorphs were computed by using the Marcus–Hush formalism. The computations of the charge-carrier-transport behaviour revealed that the S-dimer ( 25TR_(R) ) is ambipolar, whereas the C-dimer ( 25TR_(Y) ) is predominantly n-type.     

Symmetry Breaking Charge Transfer in DNA-Templated Perylene Dimer Aggregates

Molecular aggregates are of interest to a broad range of fields including light harvesting, organic optoelectronics, and nanoscale computing. In molecular aggregates, nonradiative decay pathways may emerge that were not present in the constituent molecules. Such nonradiative decay pathways may include singlet fission, excimer relaxation, and symmetry-breaking charge transfer. Singlet fission, sometimes referred to as excitation multiplication, is of great interest to the fields of energy conversion and quantum information. For example, endothermic singlet fission, which avoids energy loss, has been observed in covalently bound, linear perylene trimers and tetramers. In this work, the electronic structure and excited-state dynamics of dimers of a perylene derivative templated using DNA were investigated. Specifically, DNA Holliday junctions were used to template the aggregation of two perylene molecules covalently linked to a modified uracil nucleobase through an ethynyl group. The perylenes were templated in the form of monomer, transverse dimer, and adjacent dimer configurations. The electronic structure of the perylene monomers and dimers were characterized via steady-state absorption and fluorescence spectroscopy. Initial insights into their excited-state dynamics were gleaned from relative fluorescence intensity measurements, which indicated that a new nonradiative decay pathway emerges in the dimers. Femtosecond visible transient absorption spectroscopy was subsequently used to elucidate the excited-state dynamics. A new excited-state absorption feature grows in on the tens of picosecond timescale in the dimers, which is attributed to the formation of perylene anions and cations resulting from symmetry-breaking charge transfer. Given the close proximity required for symmetry-breaking charge transfer, the results shed promising light on the prospect of singlet fission in DNA-templated molecular aggregates.     

溶液间歇结晶过程成核与生长阶段的定量识别

为定量识别溶液间歇结晶过程中的成核和生长阶段,基于晶粒数目和粒度的变化对粒度分布(CSD)的二阶和三阶矩量影响程度的不同,定义并关联了无因次变量K和K^*.添加晶种KNO₃-H₂O溶液结晶过程模拟计算的结果表明,K和K^*值均呈先降后升的变化趋势,成核时单调下降,生长过程中单调上升;且K与K^*值较接近.测定了KNO₃-H₂O溶液自发成核结晶过程中溶液浓度和透光率的变化,用K^*判据定量识别出成核阶段和生长阶段,并与晶体线性生长速率模型检验的结果相吻合.K值的计算依赖于CSD和结晶动力学参数,而K^*作为成核和生长阶段的模型判据,由实验测定的溶液浓度和透光率计算得到.