Structure–property relationships in lath-shaped triads based on multialkynylbenzene

<p>This report elaborates the synthesis of symmetrical triads based on multialkynylbenzene linked via flexible alkyl spacers. Four mesogens were synthesised in which multialkynylbenzene units were connected to each other in a side-by-side fashion with varying flexible alkyl spacers. The compound with longest alkyl spacer, i.e. <i>n</i> = 7, exhibited <i>N</i>_D phase which has been characterised by polarised optical microscopy and detailed X-ray scattering studies (small/wide-angle X-ray scattering). Surprisingly, this triad shows <i>N</i>_D phase at high temperature as compared to our previous reports on room-temperature <i>N</i>_D phases.</p

Triphenylene-Based Room-Temperature Discotic Liquid Crystals: A New Class of Blue-Light-Emitting Materials with Long-Range Columnar Self-Assembly

A straightforward synthesis of multialkynylbenzene-bridged triphenylene-based dyad systems (via flexible alkyl spacers) that self-organize into room-temperature columnar structures over a long range is reported. The compounds with spacer lengths (<i>n</i>) of 8 and 10 exhibit a columnar rectangular mesophase whereas a compound with <i>n</i> = 6 shows a columnar rectangular plastic phase. Interestingly, the later compound (<i>n</i> = 6) shows the formation of well-nucleated spherulites of about several hundred micrometers that suggest the existence of a long-range uniform self-assembly of columns. All of these compounds show blue luminescence in solution and in the thin-film state under long-wavelength (365 nm) UV light. These compounds fulfill the described demands such as long-range columnar self-assembly at room temperature, a good yield with high purity, and blue-light emitters under the neat condition for possible potential applications in semiconductor devices. They also match the criteria of facile processing from the isotropic state because of their low isotropization temperature. This new class of materials is promising, considering the emissive nature and stabilization of the columnar mesophase at ambient temperature

TNF Induced Switching of Columnar Rectangular to Hexagonal Assemblies in a New Class of Triphenylene-Based Room Temperature Discotic Liquid Crystals

A straightforward synthesis of triphenylene-based oligomeric systems that self-organize into room temperature columnar structures is presented. The compounds with longer spacer length (<i>m</i> = 10 and 12) exhibit columnar rectangular (Col_r) mesophase whereas the compound with <i>m</i> = 8 exists in glassy Col_r state. Interestingly, the Col_r self-assembly of these compounds switches to columnar hexagonal (Col_h) on doping the compounds with 2,4,7-trinitrofluorenone (TNF). For the dopant concentration of 1:1 with respect to native compound, an intermediate transition state between Col_r and Col_h phase was observed which completely transformed into the hexagonal phase on increasing the concentration to 1:2 (compound: TNF) and afterward. Both the Col_r and Col_h self-assemblies have been well resolved by detailed X-ray analysis. These kind of oligomeric compounds generally possess a combination of desirable alignment properties analogous to monomeric compounds and long-lived glassy states similar to that of polymeric mesogens. In addition, charge hopping behavior is expected to increase in these compounds due to donor–acceptor interactions. Overall, these compounds can find possible potential applications in semiconductor devices

Transformation of Waste Toner Powder into Valuable Fe₂O₃ Nanoparticles for the Preparation of Recyclable Co(II)-NH₂‑SiO₂@Fe₂O₃ and Its Applications in the Synthesis of Polyhydroquinoline and Quinazoline Derivatives

Ecological recycling of waste materials by converting them into valuable nanomaterials can be considered a great opportunity for management and fortification of the environment. This article deals with the environment-friendly synthesis of Fe2O3 nanoparticles (composed of α-Fe2O3 and γ-Fe2O3) using waste toner powder (WTP) via calcination. Fe2O3 nanoparticles were then coated with silica using TEOS, functionalized with silane (APTMS), and immobilized with Co(II) to get the desired biocompatible and cost-effective catalyst, i.e., Co(II)-NH2-SiO2@Fe2O3. The structural features in terms of evaluation of morphology, particle size, presence of functional groups, polycrystallinity, and metal content over the surface were determined by Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (P-XRD), field emission gun-scanning electron microscopy (FEG-SEM), energy-dispersive X-ray analysis (EDX), high resolution-transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), Brunauer–Emmett–Teller (BET) analysis, and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) studies. XPS confirmed the (II) oxidation state of Co, and ICP-AES and EDX supported the loading of Co(II) over the surface of the support. P-XRD proved the polycrystalline nature of the Fe2O3 core and even after functionalization. In comparison to previously reported methods, Co(II)-NH2-SiO2@Fe2O3 provides an eco-friendly procedure for the synthesis of polyhydroquinoline and quinazoline derivatives with several advantages such as a short reaction time and high yield. Polyhydroquinoline and quinazoline derivatives are important scaffolds in pharmacologically active compounds. Moreover, the developed nanocatalyst was recyclable, and HR-TEM and P-XRD confirmed the agglomeration in the recycled catalyst resulted in a decrease in yield after the fifth run. The present protocol provides a new strategy of recycling e-waste into a heterogeneous nanocatalyst for the synthesis of heterocycles via multicomponent reactions. This made the synthesized catalyst convincingly more superior to other previously reported catalysts for organic transformations

Relative Eccentric Distance Sum/Product Indices for QSAR/QSPR: Development, Evaluation, and Application

In the present study, five detour/distance matrix based molecular descriptors (MDs) termed as relative eccentric distance sum/product indices (denoted by ^Rξ₁^SV, ^Rξ₂^SV, ^Rξ₃^SV, ^RPξ₁^SV, and ^RPξ₂^SV), as well as their topochemical versions denoted by (^Rξ₁^cSV, ^Rξ₂^cSV, ^Rξ₃^cSV, ^RPξ₁^cSV, and ^RPξ₂^cSV) have been conceptualized for exclusive use for molecules containing cyclic moieties. The said MDs exhibited exceptionally high discriminating power and high sensitivity toward branching/relative position of substituents in cyclic structures amalgamated with negligible degeneracy. Subsequently, the proposed MDs along with other MDs were successfully utilized for the development of models for the prediction of human glutaminyl cyclase (hQC) inhibitory activity using decision tree (DT), random forest (RF) and moving average analysis (MAA). A data set comprising of 45 analogues of substituted 3-(<i>1H</i>-imidazol-1-yl) propyl thiourea derivatives was used. DT identified proposed relative eccentric distance sum topochemical index-1 as the most important MD. High accuracy of prediction up to 96%, 93%, and 95% was observed in case of models derived from decision tree, random forest, and MAA, respectively. The statistical significance of proposed models was assessed through specificity, sensitivity, overall accuracy, Mathew’s correlation coefficient (MCC), and intercorrelation analysis

Tetraphenylphosphonium Bromide as a Cathode Buffer Layer Material for Highly Efficient Polymer Solar Cells

Here, we introduced the role of small organic molecule tetraphenylphosphonium bromide (<b>QPhPBr</b>) as an electron-transporting layer (ETL) material for fabricating high-efficiency bulk heterojunction polymer solar cells (PSCs). Their significantly higher power conversion efficiency (PCE) in well-known active layer devices (PTB7-Th:PC₇₁BM, PBDTTT-CT:PC₇₁BM, and P3HT:PC₇₁BM) was observed compared to that of the bare Al cathode. The use of N719 as an ETL was also demonstrated. Observed data reveal that <b>QPhPBr</b>-based devices exhibit high PCEs up to 9.18, 8.42, and 4.81% from PTB7-Th, PBDTTT-CT, and P3HT, respectively. For comparisons, the bare Al devices show PCEs of 5.37, 4.75, and 3.01%, respectively. Moreover, further enhancement of PSC efficiency (9.83, 8.69, and 5.35%) is achieved from mixed binary solution of <b>N719:QPhPBr</b> because of modulated adjustment of the work function of the Al electrode. Our results indicate the excellent function of tetraphenylphosphonium bromide and its binary blend as effective small-molecule organic materials to regulate the metal surface properties and the potential used as excellent cathode buffer layer materials for realizing high-efficiency PSCs

Perylo[1,12‑<i>b</i>,<i>c</i>,<i>d</i>] Thiophene Tetraesters: A New Class of Luminescent Columnar Liquid Crystals

Perylo­[1,12-<i>b</i>,<i>c</i>,<i>d</i>] thiophene tetraesters exhibiting wide-range hexagonal columnar phase have been synthesized. These compounds also exhibit good homeotropic alignment in the liquid-crystalline phase which is very important for the device fabrication. These compounds showed sky-blue luminescence in solution under the long-wavelength UV light. With high solubility and high quantum yield these compounds can serve as standards to measure quantum yields of unknown samples. This new class of materials is promising, considering the emissive nature and stabilization of hexagonal columnar mesophase over a wide thermal range and ease of synthesis

Fusion of Structure and Ligand Based Methods for Identification of Novel CDK2 Inhibitors

Cyclin dependent kinases play a central role in cell cycle regulation which makes them a promising target with multifarious therapeutic potential. CDK2 regulates various events of the eukaryotic cell division cycle, and the pharmacological evidence indicates that overexpression of CDK2 causes abnormal cell-cycle regulation, which is directly associated with hyperproliferation of cancer cells. Therefore, CDK2 is regarded as a potential target molecule for anticancer medication. Thus, to decline CDK2 activity by potential lead compounds has proved to be an effective treatment for cancer. The availability of a large number of X-ray crystal structures and known inhibitors of CDK2 provides a gateway to perform efficient computational studies on this target. With the aim to identify new chemical entities from commercial libraries, with increased inhibitory potency for CDK2, ligand and structure based computational drug designing approaches were applied. A druglike library of 50,000 compounds from ChemDiv and ChemBridge databases was screened against CDK2, and 110 compounds were identified using the parallel application of these models. On <i>in vitro</i> evaluation of 40 compounds, seven compounds were found to have more than 50% inhibition at 10 μM. MD studies of the hits revealed the stability of these inhibitors and pivotal role of Glu81 and Leu83 for binding with CDK2. The overall study resulted in the identification of four new chemical entities possessing CDK2 inhibitory activity

Supramolecular Interaction of Coumarin 1 Dye with Cucurbit[7]uril as Host: Combined Experimental and Theoretical Study

Molecules of the coumarin family have fluorescence characteristics that are highly sensitive to their environment, and thus, they have been used as fluorescent sensors in chemical and biological systems. However, the very poor fluorescence yield of most coumarin dyes in aqueous media limits their applications. We have adopted a supramolecular strategy to improve the fluorescence intensity of coumarin dye through its interaction with the relatively new host cucurbit[7]­uril (CB[7]). The virtually nonfluorescent coumarin 1 (Φ_f = 0.04) was converted into a highly fluorescent (Φ_f = 0.52) entity in water upon addition of the nonfluorescent host CB[7]. Various spectroscopy techniques, namely, UV–vis absorption and steady-state and time-resolved fluorescence spectroscopies, established the formation of a strong 1:1 dye–CB[7] inclusion complex with a high binding constant of (1.2 ± 0.1) × 10⁵ M^–1 for the dye. The stable inclusion complex of the neutral molecule was supported by density-functional-theory- (DFT-) based quantum chemical calculations. Energy decomposition analysis of various interaction factors in the host–guest complex revealed that key components providing stability to the complex were electrostatic, polarization, and charge-transfer energies. These new results on the formation of a strong inclusion complex of the versatile fluorophore coumarin 1 with the nontoxic host CB[7] could lead to the design of efficient molecular-scale biological probes, sensors, and photostable aqueous UV dye lasers

Liquid-Crystalline Star-Shaped Supergelator Exhibiting Aggregation-Induced Blue Light Emission

A family of closely related star-shaped stilbene-based molecules containing an amide linkage are synthesized, and their self-assembly in liquid-crystalline and gel states was investigated. The number and position of the peripheral alkyl tails were systematically varied to understand the structure–property relation. Interestingly, one of the molecules with seven peripheral chains was bimesomorphic, exhibiting columnar hexagonal and columnar rectangular phases, whereas the rest of them stabilized the room-temperature columnar hexagonal phase. The self-assembly of these molecules in liquid-crystalline and organogel states is extremely sensitive to the position and number of alkoxy tails in the periphery. Two of the compounds with six and seven peripheral tails exhibited supergelation behavior in long-chain hydrocarbon solvents. One of these compounds with seven alkyl chains was investigated further, and it has shown higher stability and moldability in the gel state. The xerogel of the same compound was characterized with the help of extensive microscopic and X-ray diffraction studies. The nanofibers in the xerogel are found to consist of molecules arranged in a lamellar fashion. Furthermore, this compound shows very weak emission in solution but an aggregation-induced emission property in the gel state. Considering the dearth of solid-state blue-light-emitting organic materials, this molecular design is promising where the self-assembly and emission in the aggregated state can be preserved. The nonsymmetric design lowers the phase-transition temperatures.The presence of an amide bond helps to stabilize columnar packing over a long range because of its polarity and intermolecular hydrogen bonding in addition to promoting organogelation