Branched Alkyl Chains Research Articles

Phase Behavior of Carbon Dioxide and Polyhedral Oligomeric Silsesquioxanes with Two Different Functional Groups

Phase behavior of carbon dioxide and polyhedral oligomeric silsesquioxanes (POSS) modified with two different functional groups is studied in the temperature range of 308-323 K, up to 22 MPa. Different than the common types, one of the eight functional groups attached to the Si atoms of these POSS is a CO2-philic functional group, methacryl, while the rest are branched alkyl chains, either isooctyl (MIOPOSS) or isobutyl (MIBPOSS). Methacrylisobutyl POSS-CO2 binary system exhibits pressure-induced melting temperature depression. Both molecules have higher solubilities in scCO2 compared to their counterparts with single type of functionality, octaisobutyl POSS, isooctyl POSS and methacryl POSS. The measured highest solubility of MIBPOSS is 0.006 mole fraction at 323 K and 16.8 MPa, while it is 0.0017 mole fraction at 323 K and 22.1 MPa for MIOPOSS. Various density-based semi-empirical models used to model the solubility data gave good correlations with AARD of about 4%.

Multi-Stimuli-Responsive Field-Effect Transistor with Conjugated Polymer Entailing Spiropyran in the Side Chains

Multi-stimuli-responsive field-effect transistors (FETs) with organic/polymeric semiconductors have received increasing attention. Herein, we report a novel strategy for fabricating multi-stimuli-r...

Combined Experimental and Density Functional Theoretical Studies of Am3+ and Eu3+ Extraction and Complexation with Different Nitrilotriacetamide (NTA) Derivatives

AbstractN,N,N′,N′,N“,N”‐hexaalkylnitrilotriacetoamide (HRNTA) derivatives were found to be promising for the separation of trivalent actinides from lanthanides, which is a burning topic in the back end of the nuclear fuel cycle. In the present work, separation of Am3+ from Eu3+ was studied using the N,N,N’,N’,N’’,N’’‐hexa‐2‐ethylhexylnitrilotriacetamide (H2EHNTA) derivative and the role of the diluent medium to control the extractable complex was demonstrated. The effect of alkyl chain length and branching in the alkyl chain of different HRNTA (R=methyl, n‐butyl, n‐hexyl, n‐dodecyl and 2‐ethylhexyl) derivatives on their complexation with Eu3+ were investigated using steady‐state and time‐resolved luminescence studies. Different species formed at different ligand to metal ratios were identified from the luminescence titration experiments and their lifetime values measured. The experimental results were corroborated with the help of density functional theoretical (DFT) calculations on Am3+ and Eu3+ complexes of HRNTA derivatives with varying alkyl chain length and branching.

Bicontinuous Cubic and Hexagonal Columnar Liquid Crystalline Ion-Conductors at Room Temperature in Ion-Doped Dendritic Amphiphiles

A bicontinuous cubic (Cubbi) liquid crystalline (LC) phase consisting of three dimensional (3D) conducting networks is a promising structural platform for ion-conductors. For practical applications using this fascinating LC structure, it is necessary to suppress crystallization at room temperature (RT). Herein, we report the Cubbi structure at RT and the morphology–dependent conduction behavior in ionic samples of a non-crystallizable dendritic amphiphile. In the molecular design, branched alkyl chains were used as an ionophobic part instead of crystallizable linear alkyl chains. Two ionic samples with Cubbi and hexagonal columnar (Colhex) LC phases at RT were prepared by adding different amounts of lithium salt to the amphiphile. Impedance analysis demonstrated that the Cubbi phase contributed to the faster ion-conduction to a larger extent than the Colhex phase due to the 3D ionic networks of the Cubbi phase. In addition, the temperature–dependent impedance and electric modulus data provided information regarding the phase transition from microphase-separated phase to molecularly mixed liquid phase.

The dissolution characteristic of nonionic surfactants in supercritical CO2

The effects of surfactant structures on the supercritical carbon dioxide (scCO2) solubility are investigated to shed some light on the application of scCO2 in chemical procedures. The dissolution pressure of three nonionic surfactants (TX45, TX100 and OP-10) in scCO2 was measured. Solubility results reveal that surfactant with branched alkyl chains shows better solubility than surfactant with linear alkyl chains. This may be due to the volumes occupied by the hydrophobic tails of these nonionic surfactants. TX45 with the largest tail volume and lowest molecular weight performs the largest solubility in scCO2. In addition, the solubility results of three nonionic surfactants in scCO2 at the temperature range of 305 K to 325 K show that solubility is proportional to the pressure and density of scCO2, and inversely proportional to the experimental temperature. Finally, two density-based models (Chrastil model and Bartle model) are applied to correlate the experimental solubility data, and the results show good agreements for the experimental data of investigated nonionic surfactants. Similar agreements with experimental solubility data of surfactants are obtained by both models and the average absolute relative deviation (AARD) values lower than 2% were obtained.

The impact of [1,2,5]chalcogenazolo[3,4‐f]‐benzo[1,2,3]triazole structure on the optoelectronic properties of conjugated polymers

AbstractTwo novel conjugated near‐infrared (NIR) absorbing donor–acceptor type copolymers comprising benzodithiophene as the donor and [1,2,5]chalcogenazolo[3,4‐f]‐benzo[1,2,3]triazole derivatives as the acceptors, spaced with thiophene as the π‐bridge, were designed and synthesized via Stille polycondensation reaction. The effect of acceptor strength on optoelectronic properties was targeted and investigated. Branched alkyl chains (the extended 2‐octyl‐1‐dodecyl alkyl chain; C8C12) were introduced to 5H‐[1,2,3]triazolo[4′,5′:4,5]benzo[1,2‐c][1,2,5]thiadiazole and 5H‐[1,2,3]triazolo[4′,5′:4,5]benzo[1,2‐c][1,2,5]selenadiazole for enhanced solubility of polymers which ease the processability hence device constructions. The strongly electron‐withdrawing units lead to a substantial change in the absorption properties via promotion of the intramolecular charge transfer band alongside the π–π* transition. The resultant soluble polymers were characterized via cyclic voltammetry to determine highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels as −5.00 and −3.92 eV for PSBT and −4.86 and −4.04 eV for PSeBT, respectively. Electronic band gaps of the copolymers were calculated as 1.08 eV for PSBT and 0.82 eV for PSeBT, respectively. NIR absorbing copolymers were used to construct electrochromic devices.

Hexahydrofarnesyl as an original bio-sourced alkyl chain for the preparation of glycosides surfactants with enhanced physicochemical properties.

Five new bio-based surfactants have been synthetized by coupling hexahydrofarnesol with mono and di-saccharides. Hexahydrofarnesol (3,7,11-trimethyl-dodecan-1-ol) is a by-product of the industrial production of farnesane, a sustainable aviation fuel obtained by a fermentation process from sugar feedstocks. Using hexahydrofarnesol as the lipophilic starting material allows obtaining 100% bio-based surfactants while valorizing an industrial by-product. Moreover, the C15-branched alkyl chain brings unique properties to the surfactants. This paper presents a physicochemical characterization of these new surfactants including their behaviors in water (water solubility, critical micellar concentration and surface tension) and in oil/water systems (interfacial tension against model oil and ternary phase behavior). Their hydrophilicities have been determined thanks to the PIT-slope method and compared to the ones of standard surfactants with linear alkyl chains, in order to distinguish the contributions of the sugar polar heads and of the branched hexahydrofarnesyl lipophilic chain. This novel class of surfactants combines the properties of sugar-based surfactants (low sensitivity to temperature and salinity, ability to form Winsor III microemulsion systems over a wide range of salinity), along with specificities linked to the branched alkyl chain (lower Krafft temperature, low surface tension).

The influence of alkyl chain branching on the properties of pyrrolidinium-based ionic electrolytes

Ionic liquids and plastic crystals based on pyrrolidinium cations are recognised for their advantageous properties such as high conductivity, low viscosity, and good electrochemical and thermal stability. The pyrrolidinium ring can be substituted with symmetric or asymmetric alkyl chain substituents to form a range of ionic liquids or plastic crystals depending on the anion. However, reports into the use of branched alkyl chains and how this influences the material properties are limited. Here, we report the synthesis of six salts - ionic liquids and organic ionic plastic crystals - where the typically used linear propyl chain substituent is replaced by the branched alternative, isopropyl, to form the cation [C(i3)mpyr]+, in combination with six different anions: dicyanamide, (fluorosulfonyl)(trifluoromethanesulfonyl)imide, bis(trifluoromethanesulfonyl)imide, bis(fluorosulfonyl)imide, tetrafluoroborate and hexafluorophosphate. The thermal and transport properties of these salts are compared to those of the analogous N-propyl-N-methylpyrrolidinium and N,N-diethylpyrrolidinium-based salts. Finally, a high lithium salt content ionic liquid electrolyte based on the bis(fluorosulfonyl)imide salt was developed. This electrolyte showed high coulombic efficiencies of lithium plating/stripping and high lithium ion transference number, making it a strong candidate for use in lithium metal batteries.

Alkyl-Group-Wrapped Unsymmetrical Squaraine Dyes for Dye-Sensitized Solar Cells: Branched Alkyl Chains Modulate the Aggregation of Dyes and Charge Recombination Processes.

Electron transfer processes at the interfaces dictate the factors that improve the photovoltaic parameters, such as open-circuit voltage (Voc) and short-circuit current (Jsc), of a dye-sensitized solar cell device, besides selection of a set of suitable anode, dye, electrolyte, and cathode materials. An inefficient charge injection process at the dye-TiO2 interface and charge recombination at the TiO2-dye/electrolyte interface have detrimental effects on improving both Jsc and Voc. Hence, tailoring the factors that govern the improvement of Jsc and Voc will be an ideal approach to get the desired sensitizers with good device efficiencies. Squaraines are far-red-active zwitterionic dyes and have a high molar extinction coefficient along with unique aggregation properties due to the large dipole moment associated with them. Here, we report a series of unsymmetrical squaraine dyes, SQS1 to SQS6, with systematic variation of alkyl groups at the sp3-C and N-atoms of the indoline unit that is away from the anchoring group to control the dye-dye interactions on the TiO2 surface. The branched alkyl groups help in modulating the self-assembly of sensitizers on the TiO2 surface, besides passivating the surface that helps avoid the charge recombination processes. Light harvesting efficiency and cyclic voltammetry studies of dye-sensitized TiO2 electrodes indicate that the aggregation and charge hopping process between the dye molecules can be modulated, respectively, by systematically increasing the number of carbon atoms in the alkyl groups. Such a variation in the branched alkyl group helps enhance Voc from 672 (SQS1) to 718 mV (SQS6) and Jsc from 7.95 (SQS1) to 12.22 mA/cm2 (SQS6), with the device efficiency ranging from 3.82% to 6.23% without any coadsorbent. Dye SQS4 achieves the highest efficiency of 7.1% (Voc = 715 mV, Jsc = 13.05 mA/cm2) with coadsorbent chenodeoxycholic acid (CDCA) using an iodine (I-/I3-) electrolyte compared to its analogues. An analysis of the incident photon-to-current efficiency profiles indicates that the major contribution to photocurrent generation is from the aggregated squaraine dyes on TiO2.

First green synthesis of (R)-2-methyl-1-phenylpropan-1-ol using whole-cell Lactobacillus paracasei BD101 biotransformation

Green chemistry includes a novel process in the production of drugs precursors and biological active molecules using biocatalysts, so reducing the threats for human sanitary and ecological pollutions. Asymmetric bioreduction of prochiral ketones by biocatalysts is one of the best prevalent used methods in synthetic organic chemistry due to the production of enantiopure chiral carbinols. This study emphasizes the application biocatalyst L paracasei BD101 for enantioselective bioreduction of 2-methyl-1-phenylpropan-1-one ketone, which contain branched alkyl chain, to (R)-2-methyl-1-phenylpropan-1-ol ((R)-2) in high yields and excellent enantiomeric excess (>99%). The scale-up production was performed, and 4.61 g of (R)-2 in enantiopure form was synthesized. L paracasei BD101 was proved to be a substantial biocatalyst in asymmetric bioreduction of a ketone which contains a branched alkyl chain. There is not any work in the literature similar to our study. Hence, it is important to work on filling this gap. This study is the first example for an enantiopure synthesis of (R)-2 by a biocatalyst. The new green method was developed for bioreduction of bulky ketones, which contains a branched alkyl chain, and it approves the synthesis of novel chiral carbinols in an easy, cheap, and environmentally friendly condition using L paracasei BD101.

Epoxy polymer toughening using dendritic spherulites microstructure formed by the self-assembly of alkyl branched tri-carbamates with a spacer of isocyanurate ring

Currently, it remains a challenge to effectively improve the toughness of epoxy polymer without impairing the processability and other properties. Herein, a novel strategy was proposed for toughening epoxy polymer using the ordered microstructure formed by the self-assembly of C8H17-alkyl branched tri-carbamates with a spacer of isocyanurate ring at relatively low concentrations in the epoxy/amine system. The employed tri-carbamates slightly affects the viscosity of the modified epoxy due to its low molecular weight and melting behavior. The dendritic spherulites microstructures self-assembled in epoxy matrix through the desired molecular interactions between branched alkyl chains, –NHCOO– and CO act as the toughening materials that absorb fracture energy and subsequently improve the impact resistance of cured epoxy without significantly sacrificing Tg and mechanic strength. Moreover, due to the good plasticization of branched C8H17- chains and excellent mechanic strength of isocyanurate ring, in-situ dispersing tri-carbamates endows the modified epoxy the balanced cured properties.

The effect of alkyl chain branching positions on the electron mobility and photovoltaic performance of naphthodithiophene diimide (NDTI)-based polymers

Conjugated polymers are widely used in organic optoelectronic devices due to their solution processability, thermal stability and structural diversity. Generally, alkyl side chains must be utilized to increase the solubility of final polymers in the processing solvent. However, the effects of different type alkyl chains on the properties of n-type photovoltaic polymers have rarely been investigated. In this article, we synthesized three naphthodithiophene diimide (NDTI) based polymers containing bulky alkyl chains with different branching position, named as NDTI-1, NDTI-2 and NDTI-3, respectively. We systematically investigated the effect of different branching point on the molecular packing, charge transport and photovoltaic performance. When moving the branching point away from the backbone, the intermolecular interaction became stronger, which could be proved by 2D grazing incidence wide angle X-ray scattering (GIWAXS) measurement. Therefore, the electron mobilities in organic field-effect transistors gradually increased from 2.11×10−3 cm2 V−1 s−1 for NDTI-1 to 4.70×10−2 cm2 V−1 s−1 for NDTI-2 and 9.27×10−2 cm2 V−1 s−1 for NDTI-3, which are quite high values for polymers with face-on orientation. In addition, the NDTI-2 and NDTI-3 thin films exhibited red-shifted absorption spectra compared with NDTI-1. When blending with three classic donor polymers PBDB-T, PTB7-Th and PE61, NDTI-2 based devices always showed the higher power conversion efficiencies (PCEs) than the other two polymers (beside the comparable result of PTB7-Th:NDTI-3 combination) as a result of the high photocurrent response and high fill factor. Our results indicate that bulky alkyl chain with branching point at 2-position should be a good and safe choice for the design of naphthodithiophene diimide-based and even naphthalene diimide-based n-type photovoltaic polymers.

Synthesis and Mesomorphic Studies of Copper(II) with Carboxylato and N-Donor Ligands

Metal containing liquid crystals also known as metallomesogens is an orientationally ordered liquid that combines properties of both crystalline state and liquid state. Three linear and one branched alkyl chain complexes of general formula [Cu2(RCOO)4(X)2], where R = CH3(CH2)13 (Complex 1, Complex 2), p-CH3(CH2)14OC6H4 (Complex 3) and CH3(CH2)7CH[(CH2)5CH3] (Complex 4), X = pyridine or 2,2-bipyridine were prepared. The single crystal X-ray crystallography of [Cu2(CH3(CH2)13COO)4(py)2] (Complex 1) shows dinuclear complexes with each square pyramidally Cu(II) centre was bridged by four carboxylato molecules and a pyridine molecule. For all complexes, the IR spectra gave the ??coo values in the range of 164 - 240 cm-1 , suggesting two binding modes of the alkylcarboxylate ligands. The UV-vis spectra shows a broad d-d band at ?max ~ 664 – 699 nm (?max ~55 – 341 M-1 cm-1 ), indicating that the distorted square pyramidal geometry at Cu(II). From the results of differential scanning calorimetry (DSC) and optical polarizing microscopy (OPM), complexes 1-4 exhibited liquid crystal mesophases.

Alkyl Chain Tuning of Small Molecule Acceptors for Efficient Organic Solar Cells

Summary The field of organic solar cells has seen rapid developments after the report of a high-efficiency (15.7%) small molecule acceptor (SMA) named Y6. In this paper, we design and synthesize a family of SMAs with an aromatic backbone identical to that of Y6 but with different alkyl chains to investigate the influence of alkyl chains on the properties and performance of the SMAs. First, we show that it is beneficial to use branched alkyl chains on the nitrogen atoms of the pyrrole motif of the Y6. In addition, the branching position of the alkyl chains also has a major influence on material and device properties. The SMA with 3rd-position branched alkyl chains (named N3) exhibits optimal solubility and electronic and morphological properties, thus yielding the best performance. Further device optimization using a ternary strategy allows us to achieve a high efficiency of 16.74% (and a certified efficiency of 16.42%).

Soft chromophore featured liquid porphyrins and their utilization toward liquid electret applications

Optoelectronically active viscous liquids are ideal for fabricating foldable/stretchable electronics owing to their excellent deformability and predictable π-unit–based optoelectronic functions, which are independent of the device shape and geometry. Here we show, unprecedented ‘liquid electret’ devices that exhibit mechanoelectrical and electroacoustic functions, as well as stretchability, have been prepared using solvent-free liquid porphyrins. The fluidic nature of the free-base alkylated-tetraphenylporphyrins was controlled by attaching flexible and bulky branched alkyl chains at different positions. Furthermore, a subtle porphyrin ring distortion that originated from the bulkiness of alkyl chains was observed. Its consequences on the electronic perturbation of the porphyrin-unit were precisely elucidated by spectroscopic techniques and theoretical modelling. This molecular design allows shielding of the porphyrin unit by insulating alkyl chains, which facilitates its corona-charged state for a long period under ambient conditions.

The structure of alkyl ester sulfonate surfactant micelles: The impact of different valence electrolytes and surfactant structure on micelle growth

The ester sulfonate anionic surfactants are a potentially valuable class of sustainable surfactants. The micellar growth, associated rheological changes, and the onset of precipitation are important consequences of the addition of electrolyte and especially multi-valent electrolytes in anionic surfactants.Small angle neutron scattering, SANS, has been used to investigate the self-assembly and the impact of different valence electrolytes on the self-assembly of a range of ester sulfonate surfactants with subtly different molecular structures.The results show that in the absence of electrolyte small globular micelles form, and in the presence of NaCl, and AlCl3 relatively modest micellar growth occurs before the onset of precipitation. The micellar growth is more pronounced for the longer unbranched and branched alkyl chain lengths. Whereas changing the headgroup geometry from methyl ester to ethyl ester has in general a less profound impact. The study highlights the importance of relative counterion binding strengths and shows how the surfactant structure affects the counterion binding and hence the micelle structure. The results have important consequences for the response of such surfactants to different operational environments.

Leaving Group Effects in a Series of Electrosprayed CcHhN1 Anthracene Derivatives.

We investigate the gas-phase structures and fragmentation pathways of model compounds of anthracene derivatives of the general formula CcHhN1 utilizing tandem mass spectrometry and computational methods. We vary the substituent alkyl chain length, composition, and degree of branching. We find substantial experimental and theoretical differences between the linear and branched congeners in terms of fragmentation thresholds, available pathways, and distribution of products. Our calculations predict that the linear substituents initially isomerize to form lower energy branched isomers prior to loss of the alkyl substituents as alkenes. The rate-determining chemistry underlying these related processes is dominated by the ability to stabilize the alkene loss transition structures. This task is more effectively undertaken by branched substituents. Consequently, analyte lability systematically increased with degree of branching (linear < secondary < tertiary). The resulting anthracen-9-ylmethaniminium ion generated from these alkene loss reactions undergoes rate-limiting proton transfer to enable expulsion of either hydrogen cyanide or CNH. The combination of the differences in primary fragmentation thresholds and degree of radical-based fragmentation processes provide a potential means of distinguishing compounds that contain branched alkyl chain substituents from those with linear ones.

Targeting human telomeric DNA with azacyanines

Small molecules targeting telomeric DNA or its interactions with telomerase have been an active area of cancer research. In the present study, we investigated the interactions of six benzimidazole compounds, called azacyanines, differing from each other in alkyl chain length and branching in the benzimidazole ring (azamethyl, azaethyl, azapropyl, azaisopropyl, azabutyl, and azaisobutyl) with human telomeric DNA (tel24) in 1:1 and 1:6 ratio (tel24:azacyanine) using UV-Vis, circular dichroism (CD), and fluorescence spectroscopy. All the compounds were binding to tel24 as indicated by the formation of the weak induced CD band between 320 nm and 360 nm. A substantial red shift and hypochromic effect were observed in the UV-Vis spectrum of azamethyl or azabutyl upon binding to tel24. No red shift or hypochromic effect was observed in the spectrum of azaisopropyl. The denaturation temperature (T$_{m})$ of tel24 increased the most, from 65~$^{\circ}$C to 78 $^{\circ}$C, in the presence of azabutyl in 1:6 ratio. Azaisopropyl stabilized tel24 the least under the same conditions. The highest (7.84 $\times $ 10$^{5} ~ \pm $ 3.44 $\times $ 10$^{4}$ M$^{-1})$ and the lowest (2.04 $\times $ 10$^{5\, }\pm $ 5.38 $\times $ 10$^{4}$ M$^{-1})$ association constants were obtained for azabutyl and azaisopropyl, respectively, by fluorescence spectroscopy. Overall, the benzimidazole scaffold, the one-pot synthesis, and the stabilization ability of azacyanines to tel24 make them plausible drug candidate molecules in targeting G-quadruplexes.

Tunable self-organization in n-type liquid crystalline dibenzocoronene tetracarboxdiimides for high photoconductivity

ABSTRACT A comprehensive study on the self-organised mesomorphism and charge-transport properties of three n-type liquid crystalline (LC) dibenzocoronene tetracarboxdiimide derivatives (Dibenzo-CDI 1, 2, 3) bearing branched alkyl chains with varied side-chain length and branching point (α or β site) has been carried out. All three Dibenzo-CDI compounds possessed high solubility in common organic solvents and low-lying lowest unoccupied molecular orbital energy levels below −4.0 eV indicating their air-stable electron-transport capacity under ambient conditions. It is discovered that the side-chain length has a moderate influence on the molecular arrangement and thus leads to only limited variation of electron-transport properties. In contrast, the branching position plays a critical role on tuning molecular packing and orientation in the bulk mesophases, thereby resulting in dramatic differences in electron mobilities. Remarkably, Dibenzo-CDI 3 demonstrates good photoconductivity by time-of-flight method with high electron mobility up to 0.075 cm2/Vs, close to the highest value reported in certain n-type LC derivatives. All these results reveal that LC Dibenzo-CDI derivatives are potential candidates for high-performance solution-processable electronics, such as air-stable n-type organic field-effect transistors (OFETs) and solar cells.

Enhancing the efficiency of mixed halide mesoporous perovskite solar cells by introducing amine modified graphene oxide buffer layer

In this study, graphene oxide (GO) was synthesized via Tour method and then modified with two different amine sources that contained different branched alkyl chains. The GO and modified GOs (mGOs) with dihexylamine (DHA) and 2-ethylhexylamine (2EHA) as amine sources were used respectively as buffer layers in mixed halide mesoporous perovskite solar cells (PSCs) in order to examine whether they could improve their performance. GO and mGO samples were characterized by several techniques such as X–Ray Diffraction, X–Ray photoelectron spectroscopy (XPS), Raman analysis and thermal gravimetric analysis (TGA). The preparation of the CH3NH3PbI3-xClx perovskite solution was performed using standard Schlenk techniques under argon atmosphere to attain a homogeneous coverage of the perovskite film. The solar cells with the additional layer of mGO derivatives between perovskite and hole transporting layer showed an improved overall performance compared to the reference devices which was attributed to the enhanced charge carrier transport via the mGOs. In particular, 10% increase to the overall performance of the solar cells was monitored in devices where 2-ethylhexylamine (2EHA) modified GO was used, compared to standard cell without buffer layer.