N-octyl Side Chain Research Articles

Synthesis of novel benzylamine antimycotics and evaluation of their antimycotic potency.

A series of 23 novel benzylamines was synthesized by reductive amination from halogen-substituted 3- and 4-benzyloxybenzaldehyde derivatives and 6-methylhept-2-yl amine or n-octylamine. The antimycotic activity of the resulting amines was evaluated in a microdilution assay against the apathogenic yeast Yarrowia lipolytica as test microorganism. Promising compounds were also tested against human pathogenic Candida species. The influence of halogen substituents at the benzyl ether side chain was studied in this screening, as well as the influence of the branched side chain of (±)-6-methylhept-2-yl amine in comparison with the n-octyl side chain.

Indacenodithienothiophene-based A-D-D′-D-A-type small-molecule donors for all-small-molecule organic solar cells

Research on all-small-molecule organic solar cells (SM-OSCs) is growing due to the advantages of small-molecule donor materials. In this study, we synthesized and characterized two small-molecule donors of A-D-D′-D-A type based on highly fused indacenodithiophene (IDTT), namely BDT-IDTT-ORH and BDT-C8IDTT-ORH. The different side chains of these two molecules, 4-hexylphenyl and n-octyl, led to different crystallinities in the film state. The two synthesized donors exhibited absorption in the long wavelength range of 400–700 nm due to effective π-conjugation caused by their planar structures. Because their absorption bands are complementary to that of the Y6 non-fullerene acceptor, these molecules showed potential as small-molecule donors in donor:Y6 blend for SM-OSCs. In particular, the BDT-C8IDTT-ORH:Y6 blend exhibited the highest power conversion efficiency (PCE) of 6.33%. This higher PCE is due to a relatively higher JSC value for BDT-C8IDTT-ORH with linear n-octyl side chains, thanks to its tighter molecular packing compared to that of BDT-IDTT-ORH with 4-hexylphenyl side chains.

N-Octyl substituted quinoxaline-based polymer donor enabling all-polymer solar cell with efficiency over 17%

Recently, the power conversion efficiencies (PCEs) of all-polymer solar cells (all-PSCs) have increased rapidly. To further increase the PCE of all-PSCs, it is necessary to create new donor polymers matching the polymer acceptors. In this paper, we synthesize a new quinoxaline-based polymer donor PBQ8 with n-octyl side chain on the quinoxaline unit, which possesses the same skeleton structure to the previously reported PBQ5 (with isooctyl side chain). The effects of alkyl side chains on the physicochemical properties of the polymer donor were investigated. In comparison with PBQ5, PBQ8 exhibits stronger intermolecular interactions and better molecular packing. When blending with polymer acceptor PY-IT, the PBQ8:PY-IT based devices demonstrated a higher PCE value of 17.04%, which is one of the highest PCEs occurred in the all-PSCs. And the PBQ5:PY-IT (PCE 15.56%, Voc 0.907 V, FF 69.72%, and Jsc 24.60 mA cm−2) is much lower. The PBQ8:PY-IT blend displayed more efficient exciton dissociation, better molecular stacking properties, preferable phase separation and higher mobility. These indicate that as an effective method, side chain engineering can improve the efficiency of the all-PSCs.

Amphiphilic Indole Derivatives as Antimycobacterial Agents: Structure-Activity Relationships and Membrane Targeting Properties.

Antibacterials that disrupt cell membrane function have the potential to eradicate "persister" organisms and delay the emergence of resistance. Here we report the antimycobacterial activities of 4-fluoro and 6-methoxyindoles bearing a cationic amphiphilic motif represented by a lipophilic n-octyl side chain at position 1 and a positively charged azepanyl or 1,4-dioxa-8-azaspiro[4.5]decane moiety at position 3. These analogues exhibited balanced profiles of potency (Mycobacterium bovis BCG, M tuberculosis H37Rv), selective activity, solubility, and metabolic stability. Bacteriological mechanism of action investigations on a representative analogue revealed cell membrane permeabilization and depolarization in M bovis BCG. These membrane-related changes preceded cell death indicating that the loss in membrane integrity was not an epiphenomenon. Bactericidal activity was observed against both growing and nongrowing mycobacterial cultures. The analogue also upregulated cell envelope stress-inducible promoters piniBAC and pclgR, implicating the involvement of envelope-related targets in its mode of action.

Poly(3-(2,5-dioctylphenyl)thiophene) Synthesized by Direct Arylation Polycondensation: End Groups, Defects, and Crystallinity

One property central to π-conjugated polymers is the ability of polymer backbones to interact intermolecularly through the direct contact of π-orbitals. Poly(3-(2,5-dioctylphenyl)thiophene) (PDOPT) is a remarkable exception as the bulky side chains prohibit main chain π–π interactions. However, due to side-chain crystallization of interdigitated n-octyl side chains, PDOPT is semicrystalline, and thus any deviation from a perfect regioregularity can severely affect crystallization. Here, we synthesize PDOPT via direct arylation polycondensation (DAP) for the first time and analyze the effect of various reaction conditions on molecular weight, end groups, defect structures, crystallinity, and morphology. Despite extensive optimization of PDOPT synthesis via DAP including bulk polymerization, MW is limited to Mn,SEC ∼ 10 kg/mol as a result of dehalogenation of chain ends. Extensive NMR spectroscopy is carried out to analyze defect structures present in PDOPT made by DAP and also made by Kumada catalyst trans...

Structure Evolution of Fluorinated Conjugated Polymers Based on Benzodithiophene and Benzothiadiazole for Photovoltaics

Two novel copolymer PTBDTffDC8TBT and PTBDTffDC8TBT-FB based on alkylthienyl benzodithiophene (TBDT) and fluorinated benzothiadiazole (ffDTBT) blocks were synthesized, and the effects of n-octyl side chains (C8) on thiophene bridge and pentafluorobenzene (FB) end group on properties of the copolymers has been investigated. With the similar properties of good thermal stability, wide spectral absorption (band gap of 1.68 eV), the molecular energy levels, and the arrangement of the polymer chains, the best pristine power conversion efficiency of PTBDTffDC8TBT-FB:PC61BM (1:1) was higher than that of PTBDTffDC8TBT, 3.6% versus 2.1%. A more optimal microphase separation morphology of PTBDTffDC8TBT-FB:PC61BM was one of the driving force to enhance the short-circuit current density (Jsc) and fill factor (FF), consequently resulting in the improved performance. Comparison of the five analogous polymers was implemented from both experiment measurement and density functional theory simulation in detail. It was demonstrated that the FB end group contributed to promote the molecule dipole moment, which benefit the exciton separation for improvement in the performance.

Amino Derivatives of Indole As Potent Inhibitors of Isoprenylcysteine Carboxyl Methyltransferase

The enzyme isoprenylcysteine carboxyl methyltransferase (Icmt) plays an important role in the post-translational modification of proteins that are involved in the regulation of cell growth. The indole acetamide cysmethynil is by far the most potent and widely investigated Icmt inhibitor, but it has modest antiproliferative activity and may have pharmacokinetic limitations due to its lipophilic character. We report here that cysmethynil can be structurally modified to give analogues that are as potent in inhibiting Icmt but with significantly greater antiproliferative activity. Key modifications were the replacement of the acetamide side chain by tertiary amino groups, the n-octyl side chain by isoprenyl and the 5-m-tolyl ring by fluorine. Moreover, these analogues have lower lipophilicities that could lead to improved pharmacokinetic profiles.

Effects of Structural Isomerism and Precursor Structures on Thermo-optic Coefficients of BPDA/PDA Polyimide Films

The effects of the structural isomerism and the alkyl side-chain lengths in the precursors of BPDA/PDA polyimide (PI) on the temperature dependence of the refractive indices (i.e. thermo-optical coefficients) have been investigated. The PIs were formed on Si substrates by thermal curing of a) poly(amic acid)s (PAA) derived from three isomers (s-, a-, and i-) of biphenyltetracarboxylic acid dianhydride (BPDA) and p-diminobenzene (PDA) and b) poly(amide alkylester)s (PAEs) having methyl-, n-propyl-, n-pentyl-, and n-octyl side chains. The TO coefficients of PIs increase as the average refractive indices and thermal expansion coefficients increase, which can be well explained with the derivative form of the Lorentz-Lorenz formula. The absolute values of TO coefficients for s-BPDA/PDA are smaller than those expected from their refractive indices, which is due to the dense molecular packing and the small coefficient of thermal expansion. Significantly larger TO coefficients were observed for the PI films prepared from PAEs than that from PAA, indicating that the larger volatile components (alcohols) eliminated during thermal imidization cause loose molecular packing in the former PIs. The use of structural isomers and chemical modification of precursors are effective to control the TO coefficients and their anisotropies in BPDA/PDA films.

Alkyl isocyanates as active site-specific reagents for serine proteases. Location of alkyl binding site in chymotrypsin by X-ray diffraction.

The structure of octylcarbamoyl-alpha-chymotrypsin to a resolution of 3.0 A is described. The n-octyl side chain of the active site directed irreversible inactivator octyl isocyanate is bound exclusively in the hydrophobic substrate binding pocket. The n-octyl isocyanate forms a planar urethane bond with the Ser-195 Ogamma and extends approximately 1 A deeper into the hydrophobic pocket than the indolyl group of indoleacryloyl-alpha-chymotrypsin (Henderson, R. (1970), J. Mol. Biol. 54, 341). All the structural changes are essentially identical with those observed in indoleacryloyl-alpha-chymotrypsin including the observation of a hydrogen bonded water molecule between the carbonyl oxygen of the octylcarbamoyl group and the imidazole group of His-57. The observed mode of n-octyl alkyl binding to chymotrypsin is consistent with the hypothesis proposed earlier (Brown, W. E. and Wold, F. (1973), Biochemistry 12, 828).