Alkoxy Side Chains Research Articles

Alkoxy-functionalized covalent organic Framework membranes for efficient molecular sieving with high water permeance

The presence of various trace water-soluble organic pollutants, such as dyes, poses significant potential risks to human health and ecosystems. Membrane technology presents a promising and sustainable approach for their removal from aqueous environments. However, the amorphous structure of most commercial membranes makes it challenging to achieve effective separation with high water flux. Here, we present a novel series of hydrophilic COF membranes with different alkoxy sidechain lengths for the first time. These alkoxy sidechain functional COF membranes exhibit efficient rejection of water-soluble organic dyes, including rose bengal (> 50 %), congo red (> 98 %), brilliant blue R250 (> 99 %), and alcian blue (> 99 %). Moreover, these membranes demonstrate a high water flux exceeding 291.8 L m-2h−1 bar−1 and exceptional long-term operational stability lasting at least 2880 min. The superior performance of COF membranes is attributed to their optimal pore size, excellent hydrophilicity, and high crystallinity. This finding offers a promising approach for effectively eliminating water-soluble organic pollutants, thereby ensuring the safety and sustainability of the water supply.

The Influence of Molecular Weights on Dispersion and Thermoelectric Performance of Alkoxy Side-Chain Polythiophene/Carbon Nanotube Composite Materials.

In the development of wearable electronic devices, the composite modification of conductive polymers and single-walled carbon nanotubes (SWCNTs) has become a burgeoning research area. This study presents the synthesis of a novel polythiophene derivative, poly(3-alkoxythiophene) (P3(TEG)T), with alkoxy side chains. Different molecular weight variants of P3(TEG)T (P1-P4) were prepared and combined with SWCNTs to form composite materials. Density functional theory (DFT) calculations revealed a reduced bandgap for P3(TEG)T. Raman spectroscopy demonstrated π-π interactions between P3(TEG)T and SWCNTs, facilitating the dispersion of single-walled carbon nanotubes and the formation of a continuous conductive network. Among the composite films, P4/SWCNTs-0.9 exhibited the highest thermoelectric performance, with a power factor (PF) value of 449.50 μW m-1 K-2. The fabricated flexible thermoelectric device achieved an output power of 3976.92 nW at 50 K, with a tensile strength of 59.34 MPa for P4/SWCNTs. Our findings highlight the strong interfacial interactions between P3(TEG)T and SWCNTs in the composite material, providing an effective charge transfer pathway. Furthermore, an improvement in the tensile performance was observed with an increase in the molecular weight of the polymer used in the composite, offering a viable platform for the development of high-performance flexible organic thermoelectric materials.

Side-chain engineering for regulating structure and properties of a novel visible-light-driven perylene diimide-based supramolecular photocatalyst

Systematic and in-depth explorations of the effects of side-chain modulation on the molecular assembly, optoelectronic properties, and photocatalytic properties of supramolecular systems, as well as the kinetics of charge separation and migration in these systems, are rare. In this study, a novel supramolecular photocatalyst with an alkoxy side chain (S-EPDI) was successfully developed through subtle design of the short and linear alkoxyl side chains, affording a phenol degradation efficiency approximately four times that of the counterpart with an alkyl side chain (S-APDI). Notably, combined density functional theory (DFT) calculations, absorption spectroscopy, and other characterizations revealed that the perylene diimide (PDI) molecular units, through π-π stacking, formed a unique rotationally offset stacked supramolecular structure, exhibiting a significant dipole moment. This gave rise to the formation of a larger inherent electric field within S-EPDI compared to S-APDI. Moreover, the study quantitatively demonstrated that a stronger inherent electric field and lower rate of surface charge recombination facilitate efficient separation of the photogenerated carriers. Therefore, the side-chain molecular engineering method employed in this study offers an effective approach for modulating the kinetics of charge migration.

Triphenylene diimides: A new class of discotic liquid crystals

Unlike the well-explored perylene diimides and naphthalene diimides, the synthesis and characterization of triphenylene diimides have not been reported to date. In this study, several di(decyloxy)-substituted triphenylene 2,3,6,7-tetracarboxyldiimides with various imide substituents were synthesized and comprehensively analyzed for their photochemical properties and mesophase behavior. It was observed that different imide substituents significantly affect self-assembly in both solution and the liquid-crystalline state. Specifically, diimide 2–1, with two n-octyl chains at the imide nitrogens, exhibits a tendency to self-assembly at relatively high concentrations in CDCl3 and displays a hexagonal columnar (Colh) phase near room temperature. Remarkably, its isomer, diimide 2–2, with two branched 2-ethylhexyl chains, exhibits an enatiotropic Colh phase with an unusually large range of 292 °C, extending from 7 °C to 299 °C. Furthermore, the study also reports two triphenylene monoimide diesters as room temperature liquid crystals, each composed of one imide, two alkoxycarbonyl, and two alkoxy side chains. These findings not only enrich the diversity of aromatic diimides but also highlight the potential applications of these novel diimides in the field of liquid crystals.

X-Ray-Sensitizers: Organic Pharmaceutical Drug Intermediates Activated Directly by X-Rays to Efficiently Populate Triplet Excitons for Cancer Treatment

Radiotherapy is an important treatment for cancer, but it is associated with major side effects due to the high dose of radiation (generally more than 50 Gy). Because radiation’s low acute and late toxicity, many tumors are treated with fractionated radiation in small doses (< 2 Gy). Scintillator X-ray-induced photodynamic therapy is an efficient methodology for cancer management that employs small doses of X-ray irradiation (< 2 Gy) in a complex process. Here we screened pharmaceutical drug intermediates that are derivatives of thioxanthone (TX) and investigated TX-derived organic pharmaceutical molecules that efficiently undergo X-ray-sensitization to populate triplet excitons (singlet oxygen) for cancer therapy when exposed to low-dose X-ray irradiation. By modifying alkoxy side chain substitutions at the 2-position to tune the molecular packing and intermolecular interactions, the fluorescence and room-temperature phosphorescence of a series of TX derivatives were assessed under X-ray irradiation. The ability of these derivatives to generate singlet oxygen and their potential for treating tumors provide new opportunities for developing organic molecules with simple chemical structures, in which large numbers of triplets can be populated directly under ultralow-dose X-ray irradiation.

Design, synthesis, and evaluation of novel quindoline derivatives with fork-shaped side chains as RNA G-quadruplex stabilizers for repressing oncogene NRAS translation

NRAS mutation is the second most common oncogenic factor in cutaneous melanoma. Inhibiting NRAS translation by stabilizing the G-quadruplex (G4) structure with small molecules seems to be a potential strategy for cancer therapy due to the NRAS protein's lack of a druggable pocket. To enhance the effects of previously reported G4 stabilizers quindoline derivatives, we designed and synthesized a novel series of quindoline derivatives with fork-shaped side chains by introducing (alkylamino)alkoxy side chains. Panels of experimental results showed that introducing a fork-shaped (alkylamino)alkoxy side chain could enhance the stabilizing abilities of the ligands against NRAS RNA G-quadruplexes and their anti-melanoma activities. One of them, 10b, exhibited good antitumor activity in the NRAS-mutant melanoma xenograft mouse model, showing the therapeutic potential of this kind of compounds.

Design and Synthesis of Dibenzothiadiazolopyrrolothiophene (DBTPT)‐Based Acceptors for Efficient Organic Photovoltaic Cells

AbstractThe central core in non‐fullerene acceptors (NFAs) plays a crucial role in determining the efficiency of organic photovoltaic (OPV) cells. To further advance the development of OPV cells, it is crucial to synthesize novel central cores for constructing high‐performance NFAs. Here, dibenzothiadiazolopyrrolothiophene (DBTPT) is introduced, a ladder‐type [1,2,5]thiadiazolo[3,4‐e]indole‐fused pentacyclic thiophene unit, into photovoltaic materials. By employing the DBTPT unit as the rigid molecular backbone and modifying the side chain of the thiophene π‐bridge, two new acceptor‐π‐acceptor’‐donor‐acceptor’‐π‐acceptor (A‐π‐A'DA’‐π‐A)‐type acceptors (T6 and T9) are synthesized. The effects of lateral alkyl and alkoxy side chains on the optoelectronic properties, charge transport, and molecular packing order are systematically investigated. When blended with polymer donor Poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b']dithiophene))‐alt‐(5,5‐(1',3'‐di‐2‐thienyl‐5'7'‐bis(2‐ethylhexyl)benzo[1',2'‐c:4',5'‐c']dithiophene‐4,8‐dione))] (PBDB‐T), the blend film based on T9 with alkoxy side chains shows favorable molecular stacking and phase separation, resulting in excellent charge transfer performance. Benefiting low energetic disorder, PBDB‐T:T9‐based cell achieves an efficiency of 12.6% with a markedly low energy loss of 0.568 eV. The preliminary results demonstrate that the DBTPT unit has great potential for the construction of novel NFAs for high‐performance OPV cells.

Novel liquid crystalline fluorene and fluorenone MIDA boronates: influence of alkyl vs alkoxy side chains on the mesomorphic properties

ABSTRACT To obtain novel boron liquid crystals, we successfully combined MIDA boronates with chromophoric fluorene and fluorenone mesogenic units and studied the influence of alkoxy versus alkyl side chains by differential scanning calorimetry (DSC), polarising optical microscopy (POM) and X-ray diffraction (XRD). The fluorenes showed broader temperature ranges of the SmA phase compared to their fluorenone counterparts. By replacing the alkoxy side chains with alkyl side chains, the mesophase ranges could be significantly enlarged and the thermal stability increased.

From non‐doped to dopable: The impact of methoxy functionalization on doping and thermoelectric properties of conjugated polymers

AbstractThe introduction of alkoxy side chains into the backbone of conjugated polymers is an effective way to change their properties. While the impact on the structure and optoelectronic properties of polymer thin films was well‐studied in organic solar cells and transistors, limited research has been conducted on their effects on doping and thermoelectric properties. In this study, the effects of methoxy functionalization of conjugated backbones on the doping and thermoelectric properties are investigated through a comparative study of diketopyrrolopyrrole‐based conjugated polymers with and without methoxy groups (P29DPP‐BTOM and P29DPP‐BT, respectively). Methoxy‐functionalization significantly enhances doping efficiency, converting undopable pairs to dopable ones. This dramatic change is attributed to the structural changes in the polymer film caused by the methoxy groups, which increases the lamellar spacing and facilitates the incorporation of dopants within the polymer crystals. Moreover, methoxy‐functionalization is advantageous in improving the Seebeck coefficient and power factor of the doped polymers, because it induces a bimodal orientational distribution in the polymer, which contributes to the increased splitting of Fermi and charge transport levels. This study demonstrates the impact of methoxy‐functionalization of a conjugated polymer on doping behavior and thermoelectric properties, providing a guideline for designing high‐performance conjugated polymers for thermoelectric applications.image

Enhancing charge transport in isoindigo-based donor–acceptor copolymers by combining ionic doping with polar alkoxy side chains

Side chains of polymers play a crucial role in manipulating polymer interchain interactions, especially polar side chains that promote strong molecular stacking and facilitate ionic diffusion.

Employment of Alkoxy Sidechains in Semicrystalline Semiconducting Polymers for Ambient-Stable p-Doped Conjugated Polymers

Employment of Alkoxy Sidechains in Semicrystalline Semiconducting Polymers for Ambient-Stable p-Doped Conjugated Polymers

Phenoxy Group-Containing Asymmetric Non-Fullerene Acceptors Achieved Higher VOC over 1.0 V through Alkoxy Side-Chain Engineering for Organic Solar Cells.

Alkoxy side chain engineering on the β-position of the thienothiophene units of Y6 derivatives plays a vital role in improving photovoltaic performances with simultaneously increasing open-circuit voltage (Voc) and fill factor (FF). In this work, we prepared a series of asymmetric non-fullerene acceptors (NFAs) by introducing alkoxy side chains and phenoxy groups on the state-of-the-art Y6-derivative BTP-BO-4F. For the comparison, 2O-BO-4F with a symmetric alkoxy side chain on the outer thiophene units and BTP-PBO-4F with an asymmetric N-attached phenoxy alkyl chain on the pyrrole ring are synthesized from BTP-BO-4F. Thereafter, we construct four asymmetric NFAs by introducing different lengths of linear/branched alkoxy chains on the β-position of the thienothiophene units of BTP-PBO-4F. The resulting NFAs, named L10-PBO, L12-PBO, B12-PBO, and B16-PBO (L = linear and B = branched alkoxy side chains), are collectively called OR-PBO-series. Unexpectedly, all OR-PBO NFAs exhibit strong edge-on molecular packing and weaker π-π interactions in the film state, which diminish the charge transfer in organic solar cell (OSC) devices. As a consequence, the optimal devices of OR-PBO-based binary blends show poor photovoltaic performances [power conversion efficiency (PCE) = 6.52-9.62%] in comparison with 2O-BO-4F (PCE = 12.42%) and BTP-PBO-4F (PCE = 15.30%) reference blends. Nevertheless, the OR-PBO-based binary devices show a higher Voc and smaller Vloss. Especially, B12-PBO- and B16-PBO-based devices achieve Voc over 1.00 V, which is the highest value of Y-series OSC devices to the best of our knowledge. Therefore, by utilizing higher Voc of OR-PBO binary blends, B12-PBO and B16-PBO are incorporated into the PM6:BTP-PBO-4F-based binary blend and fabricated ternary devices. As a result, the PM6:BTP-PBO-4F:B12-PBO ternary device delivers the best PCE of 15.60% with an increasing Voc and FF concurrently.

Tetrathiophene-based fully non-fused ring electron acceptors via asymmetric side chain engineering

Side-chain engineering has been considered as one of the most promising strategies to optimize non-fullerene acceptors. In this work, we use side-chain engineering to synthesize three fully non-fused electron acceptors (FNEAs) i.e. two symmetric acceptors (4T-BE and 4T-TO) and one asymmetric acceptor (4T-BOE) by different side chain combination onto the tetrathiophene unit, which could effectively tune the molecular conformations, electronic properties, charge carrier transport, film morphology, and photovoltaic properties. From 4T-BE to 4T-BOE and 4T-TO, the molecules present more red-shifted absorption, smaller optical bandgaps, initially rising and then declining LUMO energy levels and stronger intermolecular stacking. When blended with polymer donor PBDB-T, asymmetric 4T-BOE with alkoxy and ester side chains demonstrate a champion PCE of 9.57% with a short-circuit current density (Jsc) of 16.28 mA/cm2, an open circuit voltage (Voc) of 0.87 V, and a fill factor (FF) of 67.50%, which was higher than that of the devices based on PBDB-T:4T-BE and PBDB-T:4T-TO. These results demonstrate that asymmetric side-chain engineering is an especially crucial and effective approach for the design of highly efficient FNEAs.

Aroylhydrazone appended cinnamate based calamitic liquid crystal:Effect of alkoxy side chain and position of terminal pyridine core on mesomorphic properties

Eight newly synthesized liquid crystalline materials containing aroylhydrazone and cinnamate linking units, connected by three phenyl rings and flexible alkoxy side chains, were designed and synthesized. The confirmation of their structures was characterized by using FT-IR, 1H NMR, and 13C NMR, and elemental analysis. The phase behavior of these materials was investigated using crossed polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction techniques. Additionally, their thermal stability was assessed using thermo gravimetric analysis. In the two series of materials studied, those with shorter alkoxy side chains exhibited a smectic C phase along with a nematic mesophase, while compounds with longer alkoxy chains showed only smectic A type mesogenic behavior. The structure-property relationship of these aroylhydrazone-based homologous series was discussed to understand the impact of side alkoxy tail length and the position of the terminal isonicotinic/nicotinic hydrazide core on the liquid crystalline properties. All four materials displayed a wide temperature range of mesophases and exhibited high thermal stability. To gain further insights into their mesomorphic properties, we employed density functional theory to conduct theoretical calculations on various structural and chemical parameters of these materials, including reactivity, energy bad gap, and dipole moment.

Precise Side Chain Engineering Enabling High‐Performance Wide‐Bandgap Polymer Donors

AbstractA series of wide bandgap (WBG) conjugated polymers PTFBDT‐C, PTFBDT‐O and PTFBDT‐S are designed and synthesized with alkyl, alkoxy and thioalkyl side chains. By selecting benzodithiophene derivatives as the donor units and benzothiadiazole derivatives as the acceptor units, PTFBDT‐C, PTFBDT‐O and PTFBDT‐S are all of wide optical bandgaps. Furthermore, low bandgap small molecule L8‐BO‐4F is used as the acceptor to fabricate organic solar cells (OSCs). According to the results, PTFBDT‐C:L8‐BO‐4F blend film displays appropriate phase separation, high hole and electron mobilities, etc. Thus, the power conversion efficiency (PCE) of PTFBDT‐C:L8‐BO‐4F based OSCs is 14.02%, which is much higher than those of PTFBDT‐O:L8‐BO‐4F based (9.06%) and PTFBDT‐S:L8‐BO‐4F based ones (10.45%). These results show that the side chain engineering is an effective strategy to improve photovoltaic performance of wide bandgap polymers.

Mesomorphic Investigation of Binary Mixtures of Liquid Crystal Molecules with Different Mesogenic Architectonics

Different binary phase diagrams, made from two differently substituted three-rings azo/ester and azomethine/ester compounds of the same terminal alkoxy side chain of six carbons, as opposed to the other terminal polar substituent, which can either donate electrons or withdraw electrons including H. The thermal behavior of the prepared derivatives was investigated by differential scanning calorimetry and phases identified by polarized optical microscope. The first group of the binary mixtures was made from laterally F-substituted azo/ester derivatives and their laterally neat analogues. The second group of binary mixtures was made from laterally methoxy-substituted azomethine/ester derivatives and their laterally neat analogues. The final type of investigated phase diagrams was made from the laterally substituted azo and azomethine components bearing different lateral polar groups and different mesogenic moieties. Results were reviewed using phase diagrams that were produced and it was found that different mesomorphic characteristics were seen to depend on the mesogenic component as well as lateral and terminal polar groups. In all cases, these mixtures have been determined to have low melting-temperature eutectic compositions, while linear or negative deviation of nematic or smectic isotropic composition temperature dependence was observed.

Preparation of Laterally Chloro-Substituted Schiff Base Ester Liquid Crystals: Mesomorphic and Optical Properties

A new class of Schiff base/ester compounds: ICln, 4-((2′-chlorophenylimino)methyl)phenyl-4″-alkoxy benzoates, were synthesized and their mesophase characteristics and thermal behavior were evaluated. Differential scanning calorimetry (DSC) was used to study mesophase transitions, and polarized optical microscopy was carried out to identify the phases (POM). The results show that all compounds are monomorphic, and enantiotropic nematic (N) phases were seen at all side chains. It was found that lateral Cl atoms in the terminal benzene ring influence both conformation and mesomorphic properties. Comparisons between the present investigated lateral Cl derivatives and their laterally neat, as well as their isomeric, compounds have been briefly discussed. Results revealed that the insertion of lateral Cl substituent in the molecular structure impacts the type and stability of the formed mesophases. The exchanges of the ester-connecting moiety improve their thermal nematic stability than their previously prepared structurally isomeric derivatives. These compounds exhibit a broad absorption in the UV-Visible region, including a peak in UV region and a tail around 550 nm, and there were observed to be absorption tail increases and energy band gap decreases with the increase of the alkoxy side chain length. The photoluminescence (PL) intensity was noted to be quenched for the bulky alkoxy group ascribed to non-radiative recombination through the defect states. Moreover, time resolved fluorescence decay spectra reveal that both the radiative and non-radiative recombination lifetime increases with the increase of alkoxy side chain length.

Synthesis, characterization and photophysical study of cholesterol functionalized azo-based room temperature liquid crystals

Four new liquid crystalline materials (HA1-HA4) with cholesteryl group and azo-ester linking group interconnected with two-side substituted flexible alkoxy side chains were deliberated and synthesized. The structure confirmation of the azo mesogens was investigated by using FT-IR, 1H NMR, and 13C NMR techniques. The phase behavior of the materials was investigated by crossed polarizing optical microscopy (POM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) techniques. All four targeted materials shows smectic type mesogenic properties and further stabilized up to room temperature to lower temperature. The structure-property relationship of present azo-based materials was discussed to investigate the scope of mesogenic properties. All four materials (HA1-HA4) display wide temperature range mesophase as 52.5 °C, 54.7 °C, 52.7 °C, and 54.1 °C. The photoresponsive properties of the azo-based bi-substituted materials were well examined by UV study.

Substituents role in highly symmetrical 1,2,3-triazoles derivatives toward self-assembly of soft liquid crystals

Triazole bent-core mesogens based on symmetrical bent-shaped of two 1,2,3-triazole ring arms were synthesized and characterized. The the thermail stability of those new synthesised mesogens from the embient temperature to 215 °C giving mesogenic phase transitions over a wide temperature range is investigated. A study of different substituents located on the rigid bentcore was carried out for compact supramolecular innovated architectures which were produced by self-assembly of many triazoles soft crystals with a liquid crystals behaviour. The synthetic procedures, characterizations and polymorphism of four novel bent-core mesogens comprising symmetrical 1,2,3-triazole arms were demonstrated. The preparation process was carried out through‘‘click chemistry’’ via Cu-catalyzed azide-alkyne cycloaddition of nitro- and alkyl-substituted aromatic azides with aromatic compounds, comprising terminal alkyne groups and long alkyl or alkoxy side-chains. The triazole derivatives were fully characterized by 1H/13C NMR, Fourier-transform infrared spectroscopy (FTIR) and elemental analysis. The mesophases and textures were examined by employing polarizing optical microscope (POM), differential scanning calorimetry (DSC) and X-ray Diffraction (XRD). The analogues with shorter alkoxy terminal substituents displayed higher mesomorphic properties with wide mesomorphic temperature ranges compared to analogues with shorter alkoxy terminals. The morphological characteristics of the self-assembled triazoles were investigated by scanning electron microscopy (SEM) which demonstrated arrangement of highly ordered columnar architectures. These orders were driven by layer to next layer adjacent influences and π-π stacking. The effect of 1,2,3-triazole ring and length of terminal aliphatic chains on the liquid crystalline performance were discussed. Through an appropriate choice of lateral structures employing “click chemistry’’, both transition temperature and mesophases ranging from isotropic to columnar or B1/B4-like supramolecular liquid crystalline aggregates can be tuned.

Nafion-like structured perfluoropoly(diphenylene) graft polymers microphase separated anion exchange membranes

Perfluorinated poly(diphenyl) graft polymers with alkoxy side chains of piperidinium quaternary ammonium salts were synthesized by two-step trifluoromethanesulfonic acid and lanthanum trifluoromethanesulfonate catalyzed and Williamson ether-forming reactions. Its grafted hydrophilic side chains can form a good microphase separation structure, as demonstrated by small angle X-ray scattering and atomic force microscope. The good phase separation structure improves the ionic conductivity while ensuring a smaller swelling ratio. The ionic conductivity of long side chain polymer (PF4) reached 80 mS cm−1 at 80 °C, while the swelling ratio was only 17.1 %. The maximum power density of PF4 was 1.008 W cm−2 at a gas flow rate of 200 sccm and a gas back pressure of 0.1 MPa. In addition, due to the perfluorinated substituted backbone and the non-N-site bonded piperidine cation, all the anion exchange membranes prepared in this paper possess good alkaline stability, with a conductivity drop of no more than 11 % after 1000 h of immersion in 4 M NaOH solution, and essentially no change in mechanical properties. The PF4 was operated at a current density of 200 mA cm−2 for 250 h with a voltage drop of only 97 mV and a resistance increase of 12 %.