Modification Of Terminal Groups Research Articles

Theoretical investigation of substituted end groups in thiophene‐phenyl‐thiophene (TPT) derivatives for high efficiency organic solar cells

AbstractThe field of organic solar cells has witnessed notable advancements in the past few years, mostly due to the development of novel materials for the active layer. The current investigations reveal the potential of nine previously unexplored molecules (TP1–TP9) designed by end group modification of TPT4F molecule. These molecules were investigated at MPW1PW91/6‐31G (d, p) with DFT and TD‐DFT approach to study the various photovoltaic and geometrical parameters. The results obtained through computations indicated improvement in the investigated parameters. The terminal group modification shifted the absorption maximum towards longer wavelength in the UV‐visible region. Highly conjugated modified acceptors reduced the band gap. The lower excitation energies increased the rate of charge transfer. The designed molecules showed improved excited state lifetime in comparison to the reference. The open circuit voltage was determined using the PTB7 polymer, which exhibited a noticeable improvement, especially in TP1 (1.70 eV), TP3 (1.75 eV), TP4 (1.68 eV), TP6 (1.85 eV), and TP7 (1.75 eV) when compared with reference (1.59 eV). Moreover, charge transfer investigations of designed molecules with PTB7 complex were performed by analyzing the concentration of charge transfer over molecular orbitals, that is, HOMO to LUMO. All of the preceding investigations targeted to achieve high‐efficiency organic cells reveal that the altered molecules can be considered effective candidates to tackle future energy problems.

Enhanced Photovoltaic Properties of Y6 Derivatives with Asymmetric Terminal Groups: A Theoretical Insight.

Y6 derivatives with asymmetric terminal groups have attracted considerable attention in recent years. However, the effects of the asymmetric modification of terminal groups on the photovoltaic performance of Y6 derivatives are not well understood yet. Therefore, we designed a series of Y6-based acceptors with asymmetric terminal groups by endowing them with various electron-withdrawing abilities and different conjugated rings to conduct systematic research. The electron-withdrawing ability of the Y6-D1 terminal group (substituted by IC-2F and IC-2NO2 terminals) is strongest, followed by Y6 (substituted by two same IC-2F terminals), Y6-D2 (substituted by IC-2F and 2-(4-oxo-4,5-dihydro-6H-cyclopenta[b]thiophen-6-ylidene)malononitrile terminals), Y6-D4 (substituted by IC-2F and indene ring), and Y6-D3 (substituted by IC-2F and thiazole ring). Computed results show that A-A stacking is the main molecular packing mode of Y6 and four other asymmetric Y6 derivatives. The ratios of A-A stacking face-on configuration of Y6-D1, Y6-D2, Y6-D3, Y6-D4, and Y6 are 51.6%, 55.0%, 43.5%, 59.3%, and 62.4%, respectively. Except for Y6-D1 substituted by the IC-2F and IC-2NO2 (the strongest electron-withdrawing capacity) terminal groups, the other three asymmetric molecules are mainly electron-transporting and can therefore act as acceptors. The open-circuit voltages of organic solar cells (OSCs) based on Y6-D2, Y6-D3, and Y6-D4, except for Y6-D1, may be higher than those of OSCs based on the Y6 acceptor because of their higher energy levels of lowest unoccupied molecular orbital (LUMO). PM6/Y6-D3 and PM6/Y6-D4 have better light absorption properties than PM6/Y6 due to their higher total oscillator strength. These results indicate that Y6-D3 and Y6-D4 can be employed as good acceptors.

Carbosilane Dendrimers: Unique Models for Studying the Properties of New Polymeric Matter

The emergence of a new type of organization of polymeric matter, namely, dendrimers has led to a change in concepts about the macromolecular world. High and strictly defined functionality, monodispersity, and the cascade principle of molecular structure formation made these systems unique objects, the interest in which has not faded to date. Carbosilane dendrimers are of particular importance owing to the stability and inertness of their molecular backbone, high reactivity of functional groups at the silicon atom, and also the possibility of providing good analytical control over the forming structure. A wide variety of synthetic approaches to the modification of terminal groups allows for considering them as hybrid systems for the elucidation of structure–property relationships. Based on the results of the analysis of a large number of variations of the main strategies for the synthesis of dendrimers, this review highlights the importance of studying the relationships between structure and properties using representative homologous series of new objects as a fundamental basis for exploring the dendritic form of polymeric matter.

Upon a potential approach to regulate the targeting region of inhalable liposomes

Liposomes for inhalation have high biosafety and can achieve slow and controlled delivery, which are especially suitable for the treatment of lung diseases and have a promising clinical application prospect. However, liposomes for inhalation have the key bottleneck problem of the lack of strategies to control the targeting region, which restricts its clinical transformation. The root cause is the inability to control the bio-corona (BC) generation upon liposomes, which dominates the specific targeting regions. In order to overcome the above bottleneck, a high density hybrid liposome system based on distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)] (DSPE-PEG) may be a potential choice. The PEG chain in DSPE-PEG has “stealth” effect that can hinder the adsorption of biological molecules. When the density of DSPE-PEG hybridization is high, the “stealth” effect is more significant, and the total adsorption amount of liposomal BC can be effectively reduced. By optimizing the PEG chain structures of DSPE-PEG, viz PEG chain length and terminal group modification, DSPE-PEG high density hybrid liposomes can be endowed with the function of targeting site regulation based on BC domination effect. It is believed that this proposed system can promote the profound reform of the research paradigm of inhalational liposomes, and accelerate the development of related products.

Theoretical Study of a Two-Photon Fluorescent Probe Based on Nile Red Derivatives with Controllable Fluorescence Wavelength and Water Solubility.

Hypochloric acid (HOCl) plays a vital role in the natural defense system, but abnormal levels of it can cause cell damage, accelerated human aging, and various diseases. It is of great significance to develop new probes for detecting HOCl in biosystems nondestructively and noninvasively. The purpose of this work is to explore new chemical modification strategies of two-photon excitation fluorescence (TPEF) probes to improve the poor water solubility and low efficiency in imaging applications. Nil-OH-6 has a two-photon absorption cross-section value as high as 243 GM and attains a good quantum yield of 0.49. In addition, the modification of terminal groups with different azetidine-heterospirocycles or N,N-dialkyl fused amino groups to Nile Red can effectively improve the fluorescence efficiency as well as increase the solubility to some extent. This study provides some strategies to simultaneously improve the fluorescence performance and solubility of these two-photon probes and, hence, reliable guidance and a foundation for the subsequent synthesis of TPEF probes based on Nile Red.

Influence of the terminal group on optoelectronic properties of fused-ring nonfullerene acceptors with ethylhexyl side chain

Three fused-ring nonfullerene electron acceptors are designed and synthesized by combining side chain effect and terminal group modification. The 2-ethylhexyl substituent is employed to replace the commonly used n-hexyl or n-hexylphenyl side chains. Three acceptor units, 2-(3-oxo-2,3-dihydroinden-1-ylidene) malononitrile (IC), 2-(6-oxo-5,6-dihydro-4H-cyclopenta [c]thiophen-4-ylidene) malononitrile (CPTCN), and 2-(5,6-dichloro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (IC–2Cl) are used as the terminal groups and the three fused-ring nonfullerene acceptors, IDTC8-IC, IDTC8-Th, and IDTC8-4Cl are developed, respectively. The thermal, photophysical, electrochemical and photovoltaic properties of the three acceptors are systematically studied in view of the influence of the side chain and the terminal group. The three acceptors exhibit strong absorption ranging from 500 nm to 720 nm in solution with high molar extinction coefficients. The large bandgap polymer PM6 is chosen as the donor to blend with the acceptors, due to the complementary absorption bands and well-matched energy levels. The optimized organic solar cell based on PM6:IDTC8-IC exhibits a power conversion efficiency (PCE) of 8.56% with an open-circuit voltage (VOC) of 0.98 V, a short-circuit current density (JSC) of 13.93 mA cm−2, and a fill factor (FF) of 62.42%. The PM6:IDTC8-4Cl device demonstrates the best performance with a PCE of 9.79%, a VOC of 0.82 V, a JSC of 17.40 mA cm−2, and a FF of 68.67%. The impacts of carrier mobility, film morphology, and molecular packing properties of the blend films on photovoltaic performances are systematically investigated. The results imply that the synergistic effect of alkyl chains on the central core and modification of the terminal groups yields improved photovoltaic performance of nonfullerene acceptors.

Self-assembling 2D/2D (MXene/LDH) materials achieve ultra-high adsorption of heavy metals Ni2+ through terminal group modification

The application of two-dimensional metal carbides (MXenes) in heavy metal processing has attracted more and more attention. In this experiment, using titanium carbide as a 2D platform, an atomic-scale 2D/2D adsorbent alk-MXene/LDH was constructed by in situ mechanical self-assembly and alkali-level intercalation to remove Ni2+. Due to its unique layered structure, the oxidized functional groups and available active binding sites of MXene nanoplatelets constitute a unique adsorbent for removing heavy metals in water. The adsorption capacity of alk-MXene/LDH adsorbent for Ni2+ was 222.717 mg/g. The efficiency of Ni2+ was 97.35%, and the synthesized material could efficiently remove Ni2+ under a wide range of pH conditions (pH = 5–13). The adsorption behavior was studied using Redlich-Peterson adsorption isotherms, pseudo-second-order kinetics and thermodynamic models. In this study, the adsorbent exhibited excellent reproducibility after 8 adsorption-desorption cycles. According to the experimental results and various characterizations, the mechanism of the adsorbent was revealed. This study indicates that the atomic scale 2D/2D large basal plane has great potential in adsorbents.

Modulation of Donor Alkyl Terminal Chains with the Shifting Branching Point Leads to the Optimized Morphology and Efficient All-Small-Molecule Organic Solar Cells

Terminal group modification is one of the most influential factors for small-molecular donors compared with their polymer counterparts, resulting in an opportunity to optimize the morphology of all-small-molecule organic solar cells (ASM-OSCs). In this article, we report three novel small-molecular donors with branching points at the 1-, 2-, and 3-positions in alkyl terminal chains, called BSCl-C1, BSCl-C2, and BSCl-C3, respectively. Using IDIC-4Cl as the acceptor, the subtle branching position shift achieves a dramatic disparity in photovoltaic parameters, as indicated by the short circuit current (Jsc) changing from 4.9 to 20.1 to 14.2 mA cm-2 and the fill factor varying from 33.9 to 71.3 to 67.0% for BSCl-C1, BSCl-C2, and BSCl-C3, respectively. The best device performance of 12.40% is obtained by the BSCl-C2:IDIC-4Cl system, which not only ranks among the top values reported to date but also exhibits low energy loss in systems that use IDIC as acceptors. The notable device performance based on BSCl-C2 is attributed to the optimized phase morphology caused by the strong molecular crystallinity and suitable intermolecular interaction with IDIC-4Cl. These results demonstrate that suitably tuning the branching position of terminal groups could promote the high performance of ASM-OSCs.

SERS and DFT Study of Noble-Metal-Anchored Cys-Trp/Trp-Cys Dipeptides: Influence of Main-Chain Direction and Terminal Modifications

Tiny changes in the covalent structure of a noble-metal-anchored peptide may affect its surface-enhanced Raman scattering (SERS) signature. While SERS spectra of Cys-Trp peptides are dominated by the bands arising from the aromatic Trp side chain, a thorough study of the impact of modifications in SERS-silent regions concerning such dipeptides was yet to be performed. Thus, here we conduct an extensive SERS study of a series of Cys- and Trp-containing dipeptides, varying both the main-chain direction (Cys-Trp/Trp-Cys) and the presence of typical covalent modifications at N- and C-termini (acetylation/amidation). We use three different SERS-active substrates: oxidation–reduction cycling-roughened silver (Ag ORC), gold (Au ORC), and chemically synthesized colloidal silver nanoparticles (Ag NPs). Interpretation of the experimental data was aided with density functional theory (DFT) calculations. Potential energy distribution (PED) analysis was used for the assignment of dipeptide vibrational bands. IR and normal Raman spectra were also examined to get a complete vibrational analysis. This work may be considered the first report on the effect of terminal group modification and reversing the peptide sequence on the adsorptive behavior of dipeptide on silver and gold surface studied by SERS spectroscopy, supported by full vibrational assignment by means of the DFT method.

Design and structural modification of narrow-bandgap small molecules based on asymmetric porphyrin-diketopyrrolopyrrole backbone for solution-processed organic solar cells

Three novel organic small molecules based on asymmetric porphyrin-diketopyrrolopyrrole (DPP) backbone, namely ZnPTDPP, ZnPTDPPCN and ZnPTDPPO, have been designed and synthesized for solution-processed organic solar cells (OSCs). The terminal units of 4-cyanophenyl and 4-methoxyphenyl were introduced into ZnPTDPPCN and ZnPTDPPO respectively, and the structural modification effects on photoelectric and photovoltaic performance were fully investigated. Depending on the characteristics of porphyrin and DPP, all three molecules possess narrow bandgaps of lower than 1.50 eV, showing excellent absorption properties. Structural modification of terminal groups can effectively regulate energy levels of ZnPTDPPCN and ZnPTDPPO. As expected, extended molecular structure from D-A type to D-A-A1 or D-A-D1 type, was conducive to enlarging the π-conjugation and affecting the push-pull effect of intramolecular electrons, thus affecting the photoelectric character of materials. Solution-processed OSCs employing these molecules as the donor materials and PC61BM as the acceptor material were fabricated. It was worth mentioning that devices based on materials ZnPTDPPCN and ZnPTDPPO achieved moderate power conversion efficiencies (PCEs) of 4.26% and 4.24%, respectively, while ZnPTDPP showed an inferior PCE of 1.46%. To our knowledge, the work based on asymmetric porphyrin-DPP backbone for solution-processed OSCs, is first reported. The work will provide valuable hints for rational design of asymmetric porphyrin-based donor materials.

Terminal group modification of alkylthio substituted small molecule donor materials for organic solar cells

Side chains and terminal groups have an important effect on photovoltaic performance of organic solar cells (OSCs) based on oligothiophene donor materials. In order to study the effect of alkylthio substituent and different terminal groups on photovoltaic properties, a series of small molecules were designed and synthesized. Molecule LS0 was modified by alkyl as side chains and 2-ethylrhodanine as terminal groups while LS1a, LS1b, LS2, LS3 were substituted with alkylthio side chains and capped with different terminal groups of 2-ethylrhodanine, 2-hexylrhodanine, 2-ethylhexyl cyanoacetate, and 1,3-indanedione, respectively. Compared with LS0, alkylthio substituted LS1a exhibited higher HOMO and LUMO due to more planar backbone. Capped with different terminal groups, LS1a, LS1b, LS2, and LS3 showed the different optical and photovoltaic properties. Among these molecules, OSCs based on LS1b showed the highest power conversion efficiency (PCE) of 8.38% while others showed PCE of 7.87%, 6.52%, 6.52%, and 4.65% for LS0, LS1a, LS2, and LS3, respectively. The results demonstrated that rational selecting side chains and terminal groups could be a promising strategy to promote the performance of small molecule-based OSCs.

Bio-based Branched Polymer Bearing Castor Oil Core as a Nucleating Agent for Poly(l-Lactic Acid)

In this study, a bio-based branched polymer bearing a castor oil core was synthesized, and the nucleating effect of the branched polymer on the crystallization of poly(l-lactic acid) (PLLA) was investigated by a differential scanning calorimetry and a polarized optical microscopy. The bio-based branched polymer was synthesized by ring-opening polymerization of l-lactide using castor oil core as an initiator, and subsequently modification of terminal groups was performed. A small amount of the trimellitoyl-terminated branched polymer accelerated the crystallization of PLLA, and the crystallization half time was dependent on the molecular weight of the branched polymer. By the addition of the branched polymer, the spherulite size of PLLA became much smaller than that of neat PLLA. Furthermore, the strain at break of PLLA containing the branched polymer was improved, compared with that of neat PLLA.

PLGA–LECITHIN–PEG CORE-SHELL NANOPARTICLES FOR CANCER TARGETED THERAPY

We reported the development of multifunctional poly (lactic-co-glycolic acid) (PLGA)-lecithin-polyethylene glycol (PEG) core-shell nanoparticles (NPs) that combined the beneficial properties of liposome and polymeric NPs for chemotherapeutics delivery. The particle size, surface charge and surface functional groups were easily tunable in highly reproducible manner by various formulation parameters such as lipid/polymer, 1, 2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE)-PEG- COOH /lecithin, DSPE-PEG- COOH /DSPE-PEG- NH2mass ratio and modification of terminal groups of DSPE-PEG. We encapsulated model chemotherapy drug, hydrophilic cisplatin (DDP) or hydrophobic DDP prodrug, in the NPs and showed high encapsulation efficiency, excellent stability, specific FA targeting recognition for MCF-7 cells with over FA receptors expression and pretty cytotoxicity. Such PLGA–lecithin–PEG core-shell nanoparticles (NPs) were proved to be a promising drug delivery nanocarrier for cancer-targeted therapy.

A Facile Synthesis of Novel Pyrrolidine Dendrimers by Terminal Group Modification through 1,3-Dipolar Cycloaddition Reaction

Abstract: A series of novel dendrimers with pyrrolidine as surfacegroup has been achieved in high yields by terminal-group modifica-tion on chalcone dendrimers through the application of 1,3-dipolarcycloaddition reaction. In 1,3-dipolar cycloaddition, azomethineylides (AMY) with alkenes afforded five-membered N -methyl pyr-rolidine. The formation of N -methyl pyrrolidine in the dendriticstructure would be an important candidate in the field of biologyand pharmacology. Key words: dendrimer, pyrrolidine, chalcone, 1,3-dipolar cycload-dition Design and synthesis of dendritic architectures have beenactive areas of research because of their countless applica-tions in the field of biology and material sciences. 1–4 Den-drimers are highly branched, regularly orderedmonodisperse three-dimensional architecture. The combi-nation of discrete numbers of functionalities and high lo-cal densities of active groups in dendrimers has attracteda lot of attention from those active in medicinal chemis-try.

Nanopatterning of hydroxy-terminated self-assembled monolayer taking advantage of terminal group modification

The feasibility of using an octenyltrimethoxysilane (OCS) self-assembled monolayer (SAM) as a high-resolution electron beam (EB) resist is investigated. The vinyl groups of the OCS SAM can be modified into hydroxy groups, which are useful for biochip fabrication. The hydroxy-modified OCS SAM exhibits higher sensitivity than a vinyl-terminated one. By using the hydroxy-modified OCS SAM as an EB resist, a miniaturized pattern of 18 nm is achieved. Since the hydroxy-modified OCS SAM is repellent to many proteins, this methodology can be useful for the fabrication of protein-immobilizing templates of a molecular scale.

A novel degradable polycaprolactone networks for tissue engineering

Polycaprolactone (PCL) macromer was obtained by the reaction of PCL diol with acryloyl chloride and confirmed using Fourier transform infrared and nuclear magnetic resonance spectrometer. Novel degradable PCL networks were prepared through photopolymerization of the PCL macromer. Thermal, mechanical, and morphological characteristics as well as degradability and biocompatibility of the PCL networks were investigated. Differential scanning calorimetry showed that the melting temperature and the calculated weight average crystallinity of PCL networks were decreased with a decrease of molecular weight of PCL diols due to the increased crosslinking density. Thermal stability of PCL networks was higher than that of PCL diols. PCL networks showed faster degradation, and higher compressive modulus and compressive recovery ratios than those of PCL itself because of their low crystallinity and the modification of terminal groups. The porosity of the PCL networks can be controlled by the amounts and size of porogen used. MG-63 osteoblast cell was attached and proliferated on PCL networks. PCL networks therefore may have considerable potential as scaffold for tissue engineering.

Влияние терминальной модификации олигонуклеотидов на их стабильность в клетках микоплазм

Влияние терминальной модификации олигонуклеотидов на их стабильность в клетках микоплазм