Structure influence of alkyl chains of thienothiophene-porphyrins on the performance of organic solar cells

Two new A-D-A porphyrin derivatives,denoted as XLP-I and XLP-II,were prepared through extending theπ-conjugation of thienothiophene-porphyrin center with phenylethynyl bridges and electron-deficient ethylrhodanine terminal units,and varying the structures of alkyl chain(linear vs branched)on peripheral thienothiophene substitutions of porphyrin rings.Both molecules show strong absorption in UV–visible–near-infrared region,good thermal stability,suitable energy levels,and ordered molecular packing in solid state.In organic solar cells,PC71BM was used as electron acceptor,and porphyrin small molecules were used as electron donors.The device based on XLP-I exhibits a power conversion efficiency(PCE)of 8.30%,an open circuit voltage(Voc)of 0.894 eV,and a fill factor(FF)of 62.1%.In contrast,the device based on XLP-II presents an inferior performance with a PCE of 3.14%,a Voc of 0.847 eV,and a FF of 49.3%.The better performance of XLP-I based device is mainly attributed to its optimized film morphology,excellent absorption,and well-balanced charge transport properties.

A NEW KIND OF SURFACTANT:LONG-CHAIN ALKYLTRIPHENYLPHOSPHONIUM HALIDES Ⅲ.AN“ABNORMAL”QUENCHING OF PYRENE FLUORESCENCE BY PHOSPHONIUMS WITH DIFFERENT LENGTHS OF ALKYL CHAIN

A study of the quenching of pyrene fluorescence by a series of alkyltriphenylphosphonium bromides indi- cated the coiling conformation of ionic surfactant in aqueous solution.Formation of pyrene excimer in cetyltriph- enylphosphonium solution strengthened the conclusion.

The First Principle Study on the Rectification of Molecular Junctions Based on the Alkyl-chain-modified Phenyl Benzothiophene Derivative

Using density functional theory（DFT） combined with nonequilibrium Green＇s function investigates the electron-transport properties of several molecular junctions based on the PBTDT-CH=NH molecule, which is modified by one to four alkyl groups forming PBTDT-（CH2）nCH=NH. The electronic structures of the isolated molecules（thiol-ended PBTDT-（CH2）nCH=N） have been investigated before the electron-transport calculations are performed. The asymmetric current-voltage characteristics have been obtained for the molecular junctions. Rectifying performance of Au/S-PBTDT-CH=N-S/Au molecular junction can be regulated by introducing alkyl chain. The N3 molecular junction exhibits the best rectifying effect. Its maximum rectifying ratio is 878, which is 80 times more than that of the molecular junction based on the original N molecular junction. The current-voltage（I-V） curves of all the sandwich systems in this work are illustrated by transmission spectra and molecular projection density analysis.

π-Stacked Thermally Activated Delayed Fluorescence Emitters with Alkyl Chain Modulation

Molecules bearing separateπ-electron donor(D)and acceptor(A)groups that undergo face-to-face D/A interactions have been utilized to develop thermally activated delayed fluorescence(TADF)materials.Theseπ-stacked D/A architectures are constructed on various scaffolds,which have either a long D/A distance or permitted conrotatory motion.Here,we develop a novel spiro-based scaffold with a short D/A distance and restricted circumvolution motions because of both the rigid spiro-scaffold and large rotation hindrance between the nearly coplanar D and A.We append different alkyl chains,which can modulate charge transfer and luminescence properties,at the nitrogen of the D moiety to develop four TADF molecules,which can modulate chargetransfer and luminescence properties.Because of the introduction of the solubilized alkyl chain,these molecules were used to fabricate solutionprocessed devices,among which a maximum external quantum efficiency of 18.9%was realized.By modulating interactions between the D/A building blocks,these TADF constructs exemplify that the alkyl side chains of TADF molecules,which used to be considered as solubilizing units,have vital impact on the optoelectronic properties and thus offer a new route to the design of solution-processable TADF emitters.

Effects of anions and alkyl chain length of imidazolium-based ionic liquids at the Au(111)surface on interfacial structure:a first-principles study

The interfacial structure and adsorption mechanism of imidazolium-based ionic liquids(ILs)on Au(111)surface were investigated via first-principles calculation.Electron density analysis and Bader charge analysis were used to explore the electronic structure of Au(111)-ILs interface.Computations show that the alkyl chain length and anions play a significant role in designing Au(111)-ILs interfacial structure.On the one hand,the stability of interface and adsorption energy tend to be enhanced as the alkyl chain length increases.It attributes to the methylene group of alkyl chain which could easily anchor on the gold interface.On the other hand,the difference in anions makes the adsorption behavior quite different.The adsorption energy follows the order:[C_(n)mim][Br]>[C_(n)mim][Cl]>[Cnmim][TFSA]>[C_(n)mim][OAc]>[C_(n)mim][PF6]>[C_(n)mim][BF_(4)].The nonfluorinated ILs(containing Br,Cl,and O atoms of anions)always have a drastic charge transfer among gold-ILs interface.However,the larger van der Waals(vdWs)volumes of the fluorinated anions have a more diffused electron density which lead to the relatively weak interaction.To sum up,a detailed and systematic investigation of the variation of anions and alkyl chain length of ILs which will affect the interfacial structure is fully studied.The above study could be helpful to understand electrode-electrolyte microscopic interface and design of functional materials for energy storage.

Control of MSC Differentiation by Tuning the Alkyl Chain Length of Phe- nylboroinc Acid Based Low-molecular-weight Gelators

The physical environment plays a critical role in modulating stem cell differentiation into specific lineages. In this study, we designed and synthesized a series of low-molecular-weight gels （LMWGs） with different moduli based on phenylboronic acid derivatives. The moduli of the LMWGs were readily tuned by varying the alkyl chain without any chemical crosslinker. The cell responses to the gels were evaluated with mesenchymal stem cell （MSCs）, in respect of cell morphology, proliferation and differentiation. The prepared gels were non-toxic to MSCs, suggesting good biocompatibility. The hydrogel stiffness exerted a striking modulation effect on MSC fate decisions, where MSCs were inclined to differentiate into osteoblasts in stiff LMWGs and into chondrocytes in soft LMWGs. The pivotal elastic modulus of the LMWGs to drive MSC differentiation into osteoblastic lineage and chondrocytic lineage were approximately 20 kPa - 40 kPa and 1 kPa - 10 kPa, respectively. Overall, our results demonstrated that the modification ofhydrogel stiffness via tuning the alkyl chain was a simple but effective approach to regulate MSC differentiation into specific lineage, which might have important implications in the design of LMWGs for tissue engineering applications.

Surface hydrophobicity: effect of alkyl chain length and network homogeneity

Understanding the nature of hydrophobicity has fundamental importance in environmental applications.Using spherical silica nanoparticles(diameter=369±7 nm)as the model material,the current study investigates the relationship between the alkyl chain network and hydrophobicity.Two alkyl silanes with different chain length(triethoxymethylsilane(C1)vs.trimethoxy(octyl)silane(C8))were utilised separately for the functionalisation of the nanoparticles.Water contact angle and inverse gas chromatography results show that the alkyl chain length is essential for controlling hydrophobicity,as the octyl-functionalised nanoparticles were highly hydrophobic(water contact angle=150.6°±6.6°),whereas the methyl-functionalised nanoparticles were hydrophilic(i.e.,water contact angle=0°,similar to the pristine nanoparticles).The homogeneity of the octyl-chain network also has a significant effect on hydrophobicity,as the water contact angle was reduced significantly from 148.4°±3.5°to 30.5°±1.0°with a methyl-/octyl-silane mixture(ratio=160:40µL·g^(–1) nanoparticles).

Tuning host-guest binding model by different intramolecular alkyl chain lengths in tripodal hosts:An evidence on structure control supramolecular interactions

Supramolecular chemistry has received considerable attention in host-guest recognition.The structureresponse relationship of host-guest recognition system is a meaningful issue.Herein,a series of tripodal nitrogen mustard derivatives(TMs)have been developed in this paper.By rationally design the intramolecular alkyl chain lengths of host,the host-guest binding model have been successfully tuned,which underwent a transformation fromπ-πto multiple hydrogen bonds.This process enhances the host-guest binding force and recognition efficiency.

Inner alkyl chain modulation of small molecular acceptors enables molecular packing optimization and efficient organic solar cells

With the generation of Y6,organic solar cells have reached remarkable achievement of over 19%efficiency.Alkyl chain is of importance to modulate intermolecular stacking and possibly enhance optoelectronic properties of small molecule acceptors(SMAs).Three alkyl chains of 2-ethylhexyl,2-butylocyl and 3-ethylheptyl were selected to obtain G6-EH,G6-BO and G6-EHep molecules,respectively.Compared to G6-EH and G6-BO,G6-EHep was found inducing unfavourable large domain size.Furthermore,we discover that 2-butyloctyl effectively inhibits monomolecular and bimolecular recombination,improves molecular packing,generates more balanced carrier mobility and enhances exciton dissociation.The SMA with 2-butyloctyl alkyl chains(G6-BO)shows the best electrical and morphological characteristics,achieving a higher power conversion efficiency(PCE)of 17.06%,with an open circuit voltage of 0.912 V,a short-circuit current of 24.22 m A cm-2and a fill factor of 77.25%.Finally,using the ternary strategy by incorporating the G6-BO acceptor into PM6:BTP-e C9,we achieved a higher PCE of18.13%with enhanced electron transport.

Modulation of terminal alkyl chain length enables over 15% efficiency in small-molecule organic solar cells

In small-molecule organic solar cells(SM-OSCs),it remains a big challenge to obtain favorable bulk heterojunction morphology by donor material design.Herein,we design and synthesize three small-molecule donors BPF3T-C4,BPF3T-C6 and BPF3T-C8,with different terminal alkyl chains.Although they possess similar absorption profiles and molecular energy levels,their crystallinity gradually decreases with the chain length of the terminal alkyl chains.After blending with an electron acceptor of BO-4Cl,the crystallinity is suppressed and the packing orientations of these donors changed from edge-on to face-on.Simultaneously,the crystallinity of BO-4Cl is gradually weakened with the chain length of the terminal alkyl chain of donor materials.Finally,The BPF3T-C6 with moderate crystallinity exhibits the best phase-separation morphology among these blend films.As a result,the BPF3T-C6:BO-4Cl-based SM-OSC shows an impressive power conversion efficiency of 15.1%.

Similar or different: the same Spiro-core but different alkyl chains with apparently improved device performance of perovskite solar cells

By intelligently utilizing the odd-even effect existing in the melting points of alkanes as presented in the basic textbook of Organic Chemistry, different alkoxy groups were introduced to modify the structure of commercial Spiro-OMeTAD to give new Spiro derivatives of Spiro-OEtTAD, Spiro-OPrTAD, Spiro-OiPrTAD and Spiro-OBuTAD, with the aim to adjust the molecular packing status in perovskite solar cells as hole transporting compounds. Excitedly, with the introduction of ethoxy groups instead of the methoxy ones in Spiro-OMeTAD, Spiro-OEtTAD-based perovskite solar cells demonstrated the highest device performance of 20.16%, higher than that of Spiro-OMeTAD(18.64%).

A-π-D-π-A small-molecule donors with different end alkyl chains obtain different morphologies in organic solar cells

For bulk-heterojunction organic solar cells, the morphology of the blend films highly influence the exciton dissociation and charge transport process. In this work, two novel A-π-D-π-A(A represents the acceptor unit and D represents the donor unit) backbone structure small molecular electron donors based on two dimensional conjugated naphtho[1,2-b:5,6-b']dithiophene(NDT) with different end alkyl chains, named as NDT-3T-EH and NDT-3T-O, have been designed and synthesized. The photovoltaic property of NDT-3T-O-based device is better than that of the NDT-3T-EH and the best efficiency reaches 7.06%, and the photovoltaic property of NDT-3T-EH reaches 6.11%. The difference in the performance should be attributed to the different morphology and phase separation resulted from the different crystallinity and aggregation ability of two donors. The results demonstrate that the optimized end alkyl chains can be used to design A-π-D-π-A backbone structure small molecular electron donors for smallmolecule organic solar cells.

Modification to solution-diffusion model for performance prediction of nanofiltration of long-alkyl-chain ionic liquids aqueous solutions based on ion cluster

Mathematical modeling for nanofiltration of ionic liquids(ILs) solutions could assist to understand transfer mechanism and predict experimental values. In this work, modeling by solution-diffusion model for nanofiltration of long-alkyl-chain ILs aqueous solutions was proposed. Molecular simulations were performed to validate the existence of ion cluster in long-alkyl-chain ILs aqueous solution. Based on the results of simulations, parameters used in the solution-diffusion model were modified, such as concentration of ILs and diameter of ion cluster.The modeling process was developed for three long-alkyl-chain ILs aqueous solutions with different concentrations(1-alkyl-3-methylimidazolium chloride: [C6 mim]Cl, [C8 mim]Cl, [C10 mim]Cl). The calculated values obtained from modified solution-diffusion model could well match the experimental values.

Spatial Distributions and Potential Sources of Long Chain(C_(30),C_(32)1,15-)Alkyl Diols in Surface Sediments from Eastern China Marginal Seas

Long chain alkyl diols have shown important potential for the reconstruction of sea surface temperature,productivities and upwelling conditions in marine or lacustrine environments.However,little is known about the distribution and sources of the diols in eastern China marginal seas(CMS),which are areas of important organic carbon sink.Here the contents of C_(30) and C_(32)1,15-diols were analyzed in 181 surface sediments from eastern CMS.The similar distribution pattern and strong linear correlation between C_(30) and C_(32) diols indicated that they had similar biological source,with a dominance of C_(30) diol.Their contents ranged from 7-2726 ng g^(-1) for C_(30) diol and 5-669 ng g^(-1) for C_(32) diol,and both showed higher values mainly in the mud area of the Yellow Sea,while the TOC normalized contents showed a more obvious seaward increasing trend.The similar distribution pattern and significant positive correlation between diols and the other marine biomarkers(brassicasterol,dinosterol,C_(37) alkenones) indicated C_(30) and C_(32) diols in eastern CMS were mainly from marine algae.This conclusion was also supported by principal component analysis(PCA).Our results also showed that sediment diol contents were generally related to marine productivity,suggesting that diols could be applied for marine productivity reconstruction in eastern CMS.

Quaternary-ammonium-immobilized polystyrenes as efficient and reusable heterogeneous catalysts for synthesis of cyclic carbonate:Effects of linking chains and pendent hydroxyl group

Spherical polystyrene‐supported ammonium salts containing different linking chains between the support and ammonium groups were prepared as efficient and easily reusable heterogeneous catalysts for the cycloadditions of CO2and epoxides.The effects of the length of the linking chains and a hydroxyl group pendent on the linking chain on the catalytic performance of ionic liquid immobilized catalysts and their mechanisms were studied through experiments and density functional theory calculations.It was found that,compared with a short linking chain,a long chain can make the halogen anion more negative and provide a larger contact area of the catalysts with the reactants,thus enhancing the reaction kinetics.The hydroxyl group can stretch the C-O bonds of the epoxides,promoting the reaction thermodynamics.As a result,for the cycloaddition of propylene oxide,the yield of propylene carbonate is much higher for the catalyst with a long linking chain(yield:91.4%)compared with the yield for that with a short chain(yield:70.9%),and is further increased in the presence of pendent hydroxyl groups(yield:98.5%).The catalyst also shows a high catalytic activity even at mild temperature and good reusability(yield:≥96%for10cycles),and the selectivity is always above99%.

STUDY ON THE CATIONIC POLYMERIZATION OF 1, 3-PENTADIENE INITIATED BY AlCl_3/ALKYL HALIDE SYSTEMS

The cationic polymerizations of 1, 3-pentadiene were initiated by AlCl_3 in n-hexaneat 30℃ in the presence of alkyl halides, i.e., tert-butyl chloride, tert-butyl bromide andisobutyl chloride. The effects of these halides on the polymer yield, molecular weight,crosslinking reaction, cyclization and polymer microstructure, have been investigated. Twomain side reactions, crosslinking and cyclization, were suppressed and reduced by theaddition of the halides. The proportion of 1, 4 units of polymer chains was increasedby the presence of the halides, which reduced the polymer yield and the molecular weightof polymers.

海水条件下延展型表面活性剂降低界面张力性能研究

为系统探究海水条件下延展型表面活性剂降低界面张力的结构-性能关系,本研究选取不同结构的延展型表面活性剂进行了界面张力测试,并分别考察了疏水烷基链长、烷基支链化、氧丙烯(PO)基团数、氧乙烯(EO)基团数对降低界面张力能力的影响。结果表明,通过增加烷基链长和疏水基支链化,对界面张力降低能力影响幅度小,不能达到超低数值(<10^(-2)m N/m)。PO数是影响延展型表面活性剂降低界面张力能力的关键因素,通过长PO链段螺旋卷曲,增大疏水基尺寸,在适宜的亲水亲油平衡条件下,可以将界面张力降至10^(-3)m N/m数量级。EO基团增加不利于分子在界面上紧密排列,造成界面张力升高。原油组分在界面上的竞争吸附不利于界面张力降低,PO数增加,与原油的界面张力逐渐降低。该类表面活性剂在海水条件下依然具有高界面活性,适用于海上油藏化学驱提高采收率。

长链烷基甜菜碱表面活性剂在驱油用油水界面行为的分子模拟研究

随着化学驱规模化实施,表面活性剂的需求量猛增,而甜菜碱型表面活性剂由于其优异的界面活性、抗盐性能及绿色环保等特点,是适合油田多场景开采的一类高效驱油剂。为从分子尺度探究长链烷基甜菜碱型表面活性剂的界面活性并解释提采机制,利用分子动力学模拟研究了不同疏水链长和亲水基团的甜菜碱型表面活性剂油水界面行为和微观分子构型。通过与实验数据相互验证,为宏观实验现象提供了微观分子层面解释,并归纳了长链烷基甜菜碱型表面活性剂的界面作用机制,为根据分子模拟界面迁移及分布规律进行驱油剂设计提供指导。

我国苯乙烯合成技术研究进展

苯乙烯是一种重要的有机化工产品,广泛应用于合成树脂和合成橡胶等领域。文章介绍了我国CO_(2)氧化乙苯脱氢、苯乙炔选择性加氢、甲苯和甲醇侧链烷基化等合成苯乙烯技术的研究进展,并提出了今后的发展建议。

不同碳链长度对称双咪唑啉缓蚀剂的合成与性能研究

以月桂酸、肉豆蔻酸、棕榈酸、硬脂酸和四乙烯五胺为主要原料,反应条件为原料摩尔比1∶1.2,经酰胺化4 h,酰胺化温度150℃,环化4 h,环化温度190℃;后加入氯化苄进行材料改性,反应条件为摩尔比1∶1.2,反应时间10 h,反应温度80℃,得到烷基碳链长度分别为C11(LIRQ)、C13(MIRQ)、C15(MIRQ)、C17(PIRQ)的双对称咪唑啉缓蚀剂。采用红外光谱对其官能团结构进行表征,采用静态失重法和电化学极化曲线法,并通过透射电镜观察试片表面形貌,探究烷基链长度对缓蚀性能的影响。失重实验和极化曲线结果表明,在1 mol/L HCl介质中,随着烷基链长度增加,缓蚀剂浓度和实验温度提高其缓蚀率逐渐增加。