Terminal Phenyl Group Research Articles

Crystal structure and Hirshfeld surface analysis of 2,4-di-amino-6-[(1Z,3E)-1-cyano-2,4-di-phenyl-penta-1,3-dien-1-yl]pyridine-3,5-dicarbo-nitrile monohydrate.

The asymmetric unit of the title compound, C25H18N6·H2O, comproses two mol-ecules (I and II), together with a water mol-ecule. The terminal phenyl groups attached to the methyl groups of the mol-ecules I and II do not overlap completely, but are approximately perpendicular. In the crystal, the mol-ecules are connected by N-H⋯N, C-H⋯N, O-H⋯N and N-H⋯O hydrogen bonds with each other directly and through water mol-ecules, forming layers parallel to the (001) plane. C-H⋯π inter-actions between these layers ensure the cohesion of the crystal structure. A Hirshfeld surface analysis indicates that H⋯H (39.1% for mol-ecule I; 40.0% for mol-ecule II), C⋯H/H⋯C (26.6% for mol-ecule I and 25.8% for mol-ecule II) and N⋯H/H⋯N (24.3% for mol-ecules I and II) inter-actions are the most important contributors to the crystal packing.

Modifying the terminal phenyl group of monomethine cyanine dyes as a pathway to brighter nucleic acid probes

Three novel monomethine cyanine dyes were synthesized carrying electron donating groups to obtain even brighter nucleic acids probes.

Novel coumarin benzamides as potent and reversible monoamine oxidase-B inhibitors: Design, synthesis, and neuroprotective effects

A series of new 6-amidocoumarin derivatives, 3a–j, was synthesized and evaluated for their inhibitory activity against monoamine oxidase (MAO) and cholinesterase. All compounds, except 3 g, showed higher inhibitory activity towards MAO-B than MAO-A. Compound 3i most potently inhibited MAO-B with an IC50 value of 0.095 μM, followed by 3j (0.150 μM), 3b (0.190 μM), and 3c (0.204 μM). Compound 3i demonstrated the highest selectivity index (>421.05) for MAO-B. The remarkable MAO-B inhibitory activity of compounds 3i, 3j, 3b, and 3c highlighted the substantial role of the substituents at the 3,4-position of the terminal phenyl group in achieving optimal MAO-B inhibition, especially 3-Cl (3i) > 3-CF3 (3b). In the kinetic study, the Ki value of 3i for MAO-B was 0.046 ± 0.010 μM with a competitive reversible mode. Moreover, compounds 3i and 3j were nontoxic to normal (MDCK), cancer (HL-60), and neuroblastoma (SH-SY5Y) cells and showed protective effects against damage induced by reactive oxygen species in SH-SY5Y neuroblastoma cells. Moreover, molecular docking and molecular dynamics simulations highlighted the tight interactions of 3i with Tyr398 at the binding site of MAO-B. These findings suggest that 3i is a potent, reversible, and selective MAO-B inhibitor that could potentially treat neurological disorders.

Novel Sulfone 2-Aminobenzimidazole Derivatives and Their Coordination Compounds: Contribution of the Ethyl and Phenyl Substituents on Non-Covalent Molecular Interactions; Biological Antiproliferative Activity

New sulfone 2-aminobenzimidazole derivatives were designed and synthesized. Their nickel(II), copper(II), zinc(II), cadmium(II) and mercury(II) compounds were obtained and fully characterized by spectroscopic and analytical techniques. Single crystal X-ray structural analysis was performed in order to study the relevant intra and inter non-covalent interactions, mainly H···π, lone pair···π, and π···π, highlighting the difference between the terminal ethyl and phenyl groups in such interactions. Dimeric and trimeric supramolecular syntons were found for some of these compounds. Additionally, their antiproliferative activity was investigated, finding that the copper(II) compounds with the sulfone phenyl derivative were the most active.

Design and Pharmacological Chaperone Effects of N-(4'-Phenylbutyl)-DAB Derivatives Targeting the Lipophilic Pocket of Lysosomal Acid α-Glucosidase.

This study provides the first example of a strategy to design a practical ligand toward lysosomal acid α-glucosidase (GAA) focusing on N-alkyl derivatives of 1,4-dideoxy-1,4-imino-d-arabinitol (DAB). The optimized N-4'-(p-trifluoromethylphenyl)butyl-DAB (5g) showed a Ki value of 0.73 μM, which was 353-fold higher affinity than N-butyl-DAB (3f) without a terminal phenyl group. Docking analysis showed that the phenyl part of 5g was accommodated in a lipophilic pocket. Furthermore, the p-trifluoromethyl group effectively suppresses the fluctuation of the phenyl group, allowing it to produce a stable bonding form with GAA. 5g increased the midpoint of the protein's protein denaturation temperature (Tm) by 6.6 °C above that in the absence of the ligand and acted as a "thermodynamic stabilizer" to improve the thermal stability of rhGAA. 5g dose-dependently increased intracellular GAA activities in Pompe patient's fibroblasts with the M519V mutation; its effect was comparable to that of DNJ, which is under clinical trials.

Small Energetic Disorder Enables Ultralow Energy Losses in Non‐Fullerene Organic Solar Cells

AbstractThe relatively large non‐radiative recombination energy loss (ΔE3) is the main source of energy losses in organic solar cells (OSCs). The energetic disorder plays a crucial role in non‐radiative energy losses; however, reducing the energetic disorder by modifying terminal groups has rarely been investigated. Herein, four acceptors, BTP‐ICB1F, BTP‐ICB2F, BTP‐ICB3F, and BTP‐ICBCF3, with fluorinated phenyl terminal groups are reported at identified substitution sites. The theoretical and experimental results show that this system possesses smaller energetic disorder than the generally‐used Y6 acceptor due to the strong electron polarization effect arising from tight, 3D molecular packing. Therefore, the PM6:BTP‐ICBCF3 combination achieves high efficiency of 17.8% with high open circuit voltage (VOC) of 0.93 V and ultralow ΔE3 of 0.18 eV, which is the smallest ΔE3 for the binary OSCs with power conversion efficiency (PCEs) over 17% reported to date. Lastly, using the ternary strategy by incorporating the BTP‐ICBCF3 acceptor into PM6:BTP‐eC9, a higher PCE of 18.2% is achieved with enhanced VOC. The results imply that introducing new terminal groups in acceptors is promising for reducing energetic disorder and energy losses.

Formation of a dinuclear zinc complex with open-ring hemiporphyrazine

A dinuclear zinc complex was synthesized by the reaction of an open-ring hemiporphyrazine containing two terminal phenyl groups with zinc acetate dihydrate. Single crystal X-ray analysis revealed that the complex consists of two five-coordinated zinc ions and two open-ring ligands. The two phenyl rings in the zinc complex were found to be directed towards the benzene-ring side of the isoindoline moieties, which was in contrast to the metal-free compound with the oppositely-directed phenyl groups. The effects of metal insertion on molecular and electronic structures were investigated both experimentally and theoretically.

Development of Hydroxamate Derivatives Containing a Pyrazoline Moiety as APN Inhibitors to Overcome Angiogenesis

Aminopeptidase N (APN) was closely associated with cancer invasion, metastasis, and angiogenesis. Therefore, APN inhibitors have attracted more and more attention of scientists as antitumor agents. In the current study, we designed, synthesized, and evaluated one new series of pyrazoline-based hydroxamate derivatives as APN inhibitors. Moreover, the structure-activity relationships of those were discussed in detail. 2,6-Dichloro substituted compound 14o with R1 = CH3, showed the best capacity for inhibiting APN with an IC50 value of 0.0062 ± 0.0004 μM, which was three orders of magnitude better than that of the positive control bestatin. Compound 14o possessed both potent anti-proliferative activities against tumor cells and potent anti-angiogenic activity. At the same concentration of 50 μM, compound 14o exhibited much better capacity for inhibiting the micro-vessel growth relative to bestatin in the rat thoracic aorta ring model. Additionally, the putative interactions of 14o with the active site of APN are also discussed. The hydroxamate moiety chelated the zinc ion and formed four hydrogen bonds with His297, Glu298 and His301. Meanwhile, the terminal phenyl group and another phenyl group of 14o interacted with S2' and S1 pockets via hydrophobic effects, respectively.

EPOXY COMPOSITES REINFORCED WITH FIRE-RESISTANT DIORITE

As a result of the work, the influence of the polyfunctional modifier oligo (resorcinol phenyl phosphate) and the dispersed mineral filler diorite with terminal phenyl groups on the physicochemical and deformation -strength properties of epoxy composites was studied. The effectiveness of using diorite epoxide as an active polymer filler has been proven. The effectiveness of using diorite as an active filler in epoxy polymers, which increases strength and changes the physicochemical properties of epoxy composites, has been proven. The optimal composition of diorite was selected as a structural additive and filler in the composition of an epoxy composite (0.1 and 50 parts by weight), which strengthens the epoxy diorite composite. It has been established that the addition of diorite to the epoxy composition leads to an increase in the heat resistance of Vicat from 132ºС to 140-188ºС and increases the thermal stability of the epoxy composite, which is expressed in a shift in the initial degradation. In addition, the thermal decomposition of the composite increases the yield of carbon structures (from 54 to 70-77% by weight), prevents the pyrolysis products from entering the gas phase, which leads to a decrease in its flammability. The effectiveness of diorite surface functionalization has been proven using APTES, which provides chemical interaction at the polymer matrix/filler interface and also prevents aggregation of diorite particles.

Synthesis and hemagglutination inhibitory properties of mannose-tipped ligands: The effect of terminal phenyl groups and the linker between the mannose residue and the triazole moiety

Two families (A, B) of triazole conjugates derived from d-mannose possessing reversed linkage functionality were easily assembled by Cu(I) catalyzed azide-alkyne cycloaddition reaction (CuAAC). The mannose precursors were built with either 3-azidopropyl or propargyl aglycones whereas the phenyl moieties were built with terminal azide or propargyl groups, respectively. In a hemagglutination inhibition (HAI) assay, family A (7a-11a), where the linker between the mannose residue and the triazole ring is three carbons displayed a 3–5 fold enhancement in activity compared to family B (13a-17a) having methyl-triazolyl moiety. The representative ligand 7a, where the terminal phenyl ring is substituted with an ester group and Cl atom exhibited the highest inhibitory activity with an HAI titer of 8 μM. This compound could be a good candidate for the further design of potent mannosyl ligands targeting FimH fimbrial lectin.

New Prospective Phosphodiesterase Inhibitors: Phosphorylated Oxazole Derivatives in Treatment of Hypertension.

Purpose: One of the promising chemical groups for the development of new antihypertensive medicines, the action of which is associated with the inhibition of phosphodiesterase III (PDE3) activity, are phosphorylated oxazole derivatives (OVPs). This study aimed to prove experimentally the presence of the OVPs antihypertensive effect associated with decreasing of PDE activity and to justify its molecular mechanism. Methods: An experimental study of the effect of OVPs on phosphodiesterase activity was performed on Wistar rats. Determination of PDE activity was performed by fluorimetric method using umbelliferon in blood serum and organs. The docking method was used to investigate the potential molecular mechanisms of the antihypertensive action of OVPs with PDE3. Results: The introduction of OVP-1 50 mg/kg, as a leader compound, led to the restoration of PDE activity in the aorta, heart and serum of rats with hypertension to the values observed in the intact group. This may indicate the possibility of the development of vasodilating action of OVPs by the influence of the latter on the increase in cGMP synthesis due to inhibition of PDE activity. The calculated results of molecular docking of ligands OVPs to the active site of PDE3 showed that all test compounds have a common type of complexation due to phosphonate groups, piperidine rings, side and terminal phenyl and methylphenyl groups. Conclusion: The analysis of the obtained results both in vivo and in silico showed that phosphorylated oxazole derivatives represent a new platform for further studies as phosphodiesterase III inhibitors with antihypertensive activity.

NIR-Absorbing Electron Acceptor Based on a Selenium-Heterocyclic Core Attaching to Phenylalkyl Side Chains for Polymer Solar Cells with 17.3% Efficiency

Selenium-heterocyclic and side-chain strategies for developing near-infrared (NIR) small fused-ring acceptors (FRAs) to further obtain short-circuit current density (Jsc) have proven advantageous in the top-performing polymer solar cells (PSCs). Herein, a new electron-rich central selenium-containing heterocycle core (BTSe) attaching alkyl side chains with a terminal phenyl group was coupled with a difluorinated and dichlorinated electron-accepting terminal 1,1-dicyanomethylene-3-indanone (IC) to afford two types of new FRAs, BTSe-IC2F and BTSe-IC2Cl. Interestingly, in spite of the weaker intramolecular charge transfer, BTSe-IC2F shows a stronger NIR response because of the smaller bandgap (Egopt) up to 1.26 eV, benefiting from the stronger ordered molecular packing in comparison to BTSe-IC2Cl with an Egopt of 1.30 eV. Additionally, thermal annealing induced an evident red shift by ∼50 nm in the absorption of D18:BTSe-IC2F blend films. Such a phenomenon may be attributed to the synergistic impact of the formation of inward constriction toward the molecular backbone because of the combination of bulky side chains and fluorinated IC as well as the reduced aromaticity of the selenium heterocycle. Consequently, the thermally annealed device based on BTSe-IC2F/D18 achieves a champion power conversion efficiency (PCE) of 17.3% with a high fill factor (FF) of 77.22%, which is among the highest reported PCE values for selenium-heterocyclic FRAs in binary PSCs. The improved Jsc and FF values of the D18:BTSe-IC2F film are simultaneously achieved mainly because of the preferred face-on orientations, the well-balanced electron/hole mobility, and the favorable blend morphology compared to D18:BTSe-IC2Cl. This work suggests that the selenium-heterocyclic fused-ring core (with proper side chains) combined with fluorinated terminal groups is an effective strategy for obtaining highly efficient NIR-responsive FRAs.

Synthesis and properties of fluorene based small molecule acceptors containing aromatic malononitrile functionalities

Four novel small molecule acceptors (SMA) with fluorene-based cores were synthesized with terminal phenyl, thienyl, and furyl malononitrile groups in good yields. The products were obtained from a two-step reaction of 2,2′-(9,9-dioctyl-9H-fluorene-2,7-diyl)bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane) with m- or p-bromobenzaldehyde, 5-bromo-2-thiophenecarboxaldehyde and 5-bromo-2-furaldehyde under Suzuki conditions. Subsequent reaction with malononitrile yielded 9,9-dioctylfluorene −2,7 (1-phenyl-3(or 4)-methylene malononitrile) (m-FPM or p-FPM), 9,9-dioctylfluorene −2,7 (2-thienyl-5-methylene malononitrile) (FTM) and 9,9-dioctylfluorene −2,7 (2-furyl-5-methylene malononitrile) (FFM) respectively. Structural characterization of the compounds was performed using 1H and 13C NMR, and FT-IR. Optical and electronic characterization were done using, UV–visible and fluorescence spectroscopy, cyclic voltammetry, and DFT calculations. The compounds exhibit absorption bands ranging from 300 to 550 nm. m-FPM has the least coplanar structure while FFM displays the most coplanar structure, which increases the effective π-conjugation length resulting in a red shift of the absorption bands. The HOMO/LUMO levels were determined by CV and supported by DFT calculations, with optical band gaps of 2.70 eV and 2.41 eV for m- and p-FPM and 2.21 eV and 1.86 eV for FTM and FFM respectively. Fluorescence quenching was observed when poly-3-hexyl thiophene (P3HT) and each of the four SMAs were mixed. Films of P3HT and each SMA were cast in 1:1 and 1:4 ratios respectively. AFM indicated the formation of continuous films and the impact of small molecule structure on film morphology. These combined results indicated the capability of all of the new molecules to act as small molecule acceptors.

Tyrosine-based photoluminescent diketopiperazine supramolecular aggregates.

L-Tyrosine diketopiperazine (DKP) derivative 1 was synthesized, and the aggregation and photoluminescence behaviors were examined. A solution of 1 in tetrahydrofuran (THF) gradually became viscous at room temperature, and turned into the gel state 5 hours after preparation, as confirmed by dynamic viscoelasticity measurement. A solution of 1 in THF exhibited photoluminescence. Fibrous patterns were observed by transmission electron, atomic force and fluorescence microscopies. Dynamic light scattering, semiempirical molecular orbital and density functional theory calculations, as well as molecular dynamics simulations, indicated aggregate formation. This was attributed to intermolecular hydrogen bonding, mainly between the DKP moieties and partly between the urethane moieties, resulting in π-orbital overlap of the terminal phenyl groups leading to photoluminescence.

A Permissive Medium Chain Acyl-CoA Carboxylase Enables the Efficient Biosynthesis of Extender Units for Engineering Polyketide Carbon Scaffolds

The selective incorporation of new-to-nature extender units into polyketide synthesis is a highly effective way to engineer their carbon scaffolds. Currently, most atypical extender units are biosynthesized via reductive carboxylation of α,β-unsaturated thioesters catalyzed by crotonyl-CoA reductase/carboxylases or thioesterification of malonates by malonyl-CoA ligases followed by epimerase catalyzed enantiomerization. In this study, we identified an unusual β-subunit (Arm13) of the acyl-CoA carboxylase (ACCase) from the biosynthesis of armeniaspirols. This β-subunit is permissive to the α- and ε-subunits of propionyl-CoA carboxylase to form a fully active ACCase. Distinct from the other regular ACCases in substrate specificity, this ACCase can directly carboxylate medium chain acyl-CoAs ranging from C6 to C9 either with or without terminal substituents, e.g., alkyne or phenyl groups, to produce corresponding alkylmalonyl-CoAs with high catalytic efficiency. By harnessing the power of this ACCase in extender unit biosynthesis, we introduced structural variation into the carbon scaffold of armeniaspirols by feeding corresponding carboxylate precursors. These findings not only enrich the knowledge of the medium chain-specific ACCases but also provide an important biocatalyst for diversifying building blocks, which will greatly facilitate polyketide engineering.

Structure-Activity Relationship Studies on Novel Antiviral Agents for Norovirus Infections.

Human norovirus is the leading cause of acute gastroenteritis worldwide, affecting every year 685 million people. Norovirus outbreaks are associated with very significant economic losses, with an estimated societal cost of 60 billion USD per year. Despite this, no therapeutic options or vaccines are currently available to treat or prevent this infection. An antiviral therapy that can be used as treatment and as a prophylactic measure in the case of outbreaks is urgently needed. We previously described the computer-aided design and synthesis of novel small-molecule agents able to inhibit the replication of human norovirus in cell-based systems. These compounds are non-nucleoside inhibitors of the viral polymerase and are characterized by a terminal para-substituted phenyl group connected to a central phenyl ring by an amide-thioamide linker, and a terminal thiophene ring. Here we describe new modifications of these scaffolds focused on exploring the role of the substituent at the para position of the terminal phenyl ring and on removing the thioamide portion of the amide-thioamide linker, to further explore structure-activity relationships (SARs) and improve antiviral properties. According to three to four-step synthetic routes, we prepared thirty novel compounds, which were then evaluated against the replication of both murine (MNV) and human (HuNoV) norovirus in cells. Derivatives in which the terminal phenyl group has been replaced by an unsubstituted benzoxazole or indole, and the thioamide component of the amide-thioamide linker has been removed, showed promising results in inhibiting HuNoV replication at low micromolar concentrations. Particularly, compound 28 was found to have an EC50 against HuNoV of 0.9 µM. Although the most active novel derivatives were also associated with an increased cytotoxicity in the human cell line, these compounds represent a very promising starting point for the development of new analogues with reduced cytotoxicity and improved selectivity indexes. In addition, the experimental biological data have been used to create an initial 3D quantitative structure-activity relationship model, which could be used to guide the future design of novel potential anti-norovirus agents.

Distance Matters: Biasing Mechanism, Transfer of Asymmetry, and Stereomutation in N-Annulated Perylene Bisimide Supramolecular Polymers.

The synthesis of two series of N-annulated perylene bisimides (PBIs), compounds 1 and 2, is reported, and their self-assembling features are thoroughly investigated by a complete set of spectroscopic measurements and theoretical calculations. The study corroborates the enormous influence that the distance between the PBI core and the peripheral groups exerts on the chiroptical properties and the supramolecular polymerization mechanism. Compounds 1, with the peripheral groups separated from the central PBI core by two methylenes and an ester group, form J-type supramolecular polymers in a cooperative manner but exhibit negligible chiroptical properties. The lack of clear helicity, due to the staircase arrangement of the self-assembling units in the aggregate, justifies these features. In contrast, attaching the peripheral groups directly to the N-annulated PBI core drastically changes the self-assembling properties of compounds 2, which form H-type aggregates following an isodesmic mechanism. These H-type aggregates show a strong aggregation-caused quenching (ACQ) effect that leads to nonemissive aggregates. Chiral (S)-2 and (R)-2 experience an efficient transfer of asymmetry to afford P- and M-type aggregates, respectively, although no amplification of asymmetry is achieved in majority rules or “sergeants-and-soldiers” experiments. A solvent-controlled stereomutation is observed for chiral (S)-2 and (R)-2, which form helical supramolecular polymers of different handedness depending on the solvent (methylcyclohexane or toluene). The stereomutation is accounted for by considering the two possible conformations of the terminal phenyl groups, eclipsed or staggered, which lead to linear or helical self-assemblies, respectively, with different relative stabilities depending on the solvent.

Development and Analysis of the Physicochemical and Mechanical Properties of Diorite-Reinforced Epoxy Composites.

The aim of this paper is to study the effect of a polyfunctional modifier oligo (resorcinol phenyl phosphate) with terminal phenyl groups and a dispersed mineral filler, diorite, on the physicochemical and deformation-strength properties of epoxy-based composites. The efficiency of using diorite as an active filler of an epoxy polymer, ensuring an increase in strength and a change in the physicochemical properties of epoxy composites, has been proven. We selected the optimal content of diorite both as a structuring additive and as a filler in the composition of the epoxy composite (0.1 and 50 parts by mass), at which diorite reinforces the epoxy composite. It has been found that the addition of diorite into the epoxy composite results in an increase in the Vicat heat resistance from 132 to 140–188 °C and increases the thermal stability of the epoxy composite, which is observed in a shift of the initial destruction temperature to higher temperatures. Furthermore, during the thermal destruction of the composite, the yield of carbonized structures increases (from 54 to 70–77% of the mass), preventing the release of volatile pyrolysis products into the gas phase, which leads to a decrease in the flammability of the epoxy composite. The efficiency of the functionalization of the diorite surface with APTES has been proven, which ensures chemical interaction at the polymer matrix/filler interface and also prevents the aggregation of diorite particles, which, in general, provides an increase in the strength characteristics of epoxy-based composite materials by 10–48%.

α-d-Mannoside ligands with a valency ranging from one to three: Synthesis and hemagglutination inhibitory properties

Six mono-, di-, and trivalent α-d-mannopyranosyl conjugates built on aromatic scaffolds were synthesized in excellent yields by Cu(I) catalyzed azide-alkyne cycloaddition reaction (CuAAC). These conjugates were designed to have unique, flexible tails that combine a mid-tail triazole ring, to interact with the tyrosine gate, with a terminal phenyl group armed with benzylic hydroxyl groups to avoid solubility problems as well as to provide options to connect to other supports. Biological evaluation of the prepared conjugates in hemagglutination inhibition (HAI) assay revealed that potency increases with valency and the trivalent ligand 6d (HAI = 0.005 mM) is approximately sevenfold better than the best meta-oriented monovalent analogues 2d and 4d (HAI ≈ 0.033 mM) and so may serve as a good starting point to find new lead ligands.

Effect of replacing the terminal phenyl ring with 3-pyridyl and inversion of imine linkage on the mesophase behaviour of four-ring azo/ester/Schiff base compounds

ABSTRACT In the present work two homologue series of four-ring azo/ester/imine compounds; namely, 4-(4′–alkoxy–phenylazo) phenyl–4′′–(benzylidene–amino) benzoate, I n, and 4–(4′–alkoxy–phenylazo) phenyl–4′′–[(pyridin-3–ylmethylene)–amino] benzoate, II n, were prepared and investigated for their mesophase behaviour. In these two types of homologue series, the length of the terminal alkoxy group (n) varies between 6 and 16 carbons. Compounds prepared in both series were structurally characterised via thermogravimetric and elemental analyses, FTIR, 1H-NMR, and mass spectroscopy. Their mesophase transition temperatures were determined by differential scanning calorimetry (DSC), whereas, the type of the mesophase was identified by polarised light microscopy (PLM). The molecular structure–property relationship was conducted aiming to investigate the effect of replacing the terminal phenyl group in I n with a pyridyl one in II n, in addition to the effect of variation of the alkoxy chain length. Aiming to investigate the effect of inversion of the methineazo group on the mesophase behaviour of the compounds, a comparison was made between the prepared series of compounds (I n) with previously prepared four rings 4-(4′-alkoxyphenylazo)–phenyl 4′′–phenyliminomethyl–benzoate phenyl-4ʹ-(4′′-alkoxyphenylazo) benzoate, III n. Finally, the mesophases of series II n were compared with their corresponding three-ring analogues, 4-(4′-alkoxy phenyl −4′′-[(pyridin-4-ylmethylene)–amino] benzoate analogues (IV n).