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Two structural isomeric porphyrin-based triads (Zn(II)porphyrin−Sn(IV)porphyrin−Zn(II)porphyrin) denoted as T1 and T2 were prepared from the reaction of meso-[5-(4-hydroxyphenyl)-10,15,20-tris(3,5-di-tert-butylphenyl)porphyrinato]zinc(II) (ZnL) with trans-dihydroxo-[5,10-bis(3-pyridyl)-15,20-bis(phenyl)porphyrinato]tin(IV) (SnP1) and trans-dihydroxo-[5,15-bis(3-pyridyl)-10,20-bis(phenyl)porphyrinato]tin(IV) (SnP2), respectively. All the compounds were characterized using UV–vis spectroscopy, emission spectroscopy, ESI−MS, 1H NMR spectroscopy, and FE-SEM. Most importantly, the two structurally isomeric porphyrin-based triads supramolecularly self-assembled into completely different nanostructures. T1 exhibits a nanosphere morphology, whereas T2 exhibits a nanofiber morphology. The amplified geometric feature in the structural isomeric porphyrin-based triads dictates the physical and chemical properties of the two triads. Both compounds showed the morphology-dependent visible light catalytic photodegradation of rhodamine B dye (74–97% within 90 min) and tetracycline antibiotic (44–71% within 45 min) in water. In both cases, the photodegradation efficiency of T2 was higher than that of T1. The present investigation can significantly contribute to the remediation of wastewater by tuning the conformational changes in porphyrin-based photocatalysts. [ABSTRACT FROM AUTHOR]

The impact of isomerism of pyrimidine-based ligands and their rhodium(III) complexes with regard to their structures and properties was investigated. Two isomeric ligands, 4-(3,5-dimethyl-1H-pyrazol-1-yl)-2,5-diphenylpyrimidine (HL2,5) and 4-(3,5-dimethyl-1H-pyrazol-1-yl)-2,6-diphenylpyrimidine (HL2,6), were synthesized. The ligands differ by the degree of steric bulk: the molecular structure of HL2,5 is more distorted due to presence of pyrazolyl and phenyl groups in the neighbouring positions 4 and 5 of the pyrimidine ring. The complexation of HL2,5 and HL2,6 with RhCl3 leads to the sp2 C–H bond activation, resulting in the isolation of two complexes, [RhL2,5(Solv)Cl2]·nEtOH and [RhL2,6(Solv)Cl2]·nEtOH (Solv = H2O, EtOH), with the deprotonated forms of the pyrazolylpyrimidine molecules which coordinate the Rh3+ ion as N^N^C-tridentate ligands. According to DFT modelling, the mechanism of the deprotonation involves (i) the C–H bond breaking in the 2-phenyl group followed by the coordination of the C atom to the Rh atom, (ii) the protonation of coordinated chlorido ligand, (iii) the ejection of the HCl molecule and (iv) the coordination of the H2O molecule. The ligand isomerism has an impact on emission properties and cytotoxicity of the complexes. Although the excited states of the complexes effectively deactivate through S0/T1 and S0/S1 crossings associated with the cleavage of the weak H2O ligands upon excitation, the [RhL2,5(Solv)Cl2]·nEtOH complex appeared to be emissive in the solid state, while [RhL2,6(Solv)Cl2]·nEtOH is non-emissive at all. The complexes show significant cytotoxic activity against cancerous HepG2 and Hep2 cell lines, with the [RhL2,6(Solv)Cl2]·nEtOH complex being more active than its isomer [RhL2,5(Solv)Cl2]·nEtOH. On the other hand, noticeable cytotoxicity of the latter against HepG2 is supplemented by its non-toxicity against non-cancerous MRC-5 cells. [ABSTRACT FROM AUTHOR]

The development of multifunctional thermally activated delayed fluorescence (TADF) material with high efficiency is indeed a formidable challenge. The difficulty arises from the need to achieve multiple desirable radiation pathways simultaneously during the emission process. In this context, a novel strategy to construct multifunctional emitters with high emission efficiency by modulating intramolecular halogen bonding through structural isomerism is proposed. The designed molecule DMAC‐2FDPS exhibits multifunctional features, including aggregation‐induced emission, mechanochromic luminescence, room temperature phosphorescence, mechanoluminescence, and TADF. Notably, in neat film, DMAC‐2FDPS demonstrates an exceptionally high photoluminescence quantum efficiency of up to 93%. Through single‐crystal analysis and theoretical calculations, it is revealed that the intramolecular halogen bonding in this molecule plays a crucial role in achieving both multifunctional emission and high PLQY. Furthermore, when utilized in non‐doped organic light‐emitting diodes (OLEDs), DMAC‐2FDPS achieves a maximum external quantum efficiency of up to 21.2%. To the best acknowledge, it is almost the highest efficiency for non‐doped OLEDs based on multifunctional materials with five characteristics. These results certify a new strategy for the development of high‐efficiency multifunctional TADF materials and devices. [ABSTRACT FROM AUTHOR]

The stepwise addition of increasing amounts of Au(PPh3)Cl to [HRu4(CO)12]3− (1) results in the sequential formation of [HRu4(CO)12(AuPPh3)]2− (2), [HRu4(CO)12(AuPPh3)2]− (3), and HRu4(CO)12(AuPPh3)3 (4). Alternatively, 4 can be obtained upon addition of HBF4·Et2O (two mole equivalents) to 3. Further addition of acid to 3 (three mole equivalents) results in the formation of the tetra-aurated cluster Ru4(CO)12(AuPPh3)4 (5). Compounds 2–5 have been characterized by IR, 1H and 31P{1H} NMR spectroscopies. Moreover, the molecular structures of 3–5 have been determined by single crystal X-ray diffraction as [NEt4][3]·2CH2Cl2, 4-b·2CH2Cl2, 4-a, 5·0.5CH2Cl2·solv, and 5·solv crystalline solids. Two different isomers of 4, that is 4-a and 4-b, have been crystallographically characterized and their rapid interconversion in solution was studied by variable temperature 1H and 31P{1H} NMR spectroscopies. Weak aurophilic Au⋯Au contacts have been detected in the solid state structures of 3–5. Computational studies have been performed in order to elucidate bonding and isomerism, as well as to predict the possible structure of the elusive species 2. [ABSTRACT FROM AUTHOR]

[Display omitted] Isomerism is an essential and ubiquitous phenomenon in organic chemistry, yet it is rarely observed in covalent organic frameworks (COFs). Herein, we synthesized two framework-isomeric COFs (BATD-Dma-COF-K and BATD-Dma-COF-R) and found for the first time that the light scattering signal of the COFs can be used for the analytical detection of lead ion. By using solvothermal and room temperature solvent synthesis methods, controlling different synthesis conditions, and introducing regulators to increase the energy difference between different products, the product with the lowest energy could be synthesized under specific conditions. This method could control the morphology of the synthesized COF and realize the precise synthesis of framework-isomeric COF by changing the experimental conditions. The structures of the two framework-isomeric COFs were characterized and confirmed by a series of analytical methods. Based on the principle that lead ions coordinate with N and O on the surface of two skeletal isomers BATD-Dma-COFs to enhance the light scattering signal of the COFs, a light scattering probe was developed by BATD-Dma-COF for the detection of metal lead ion in water samples. Lead ion concentration in the range from 2.0 to 250.0 μM had a good linear relationship with the light scattering intensity increase of the COFs with detection limit as low as 0.8397 μM by BATD-Dma-COF-K and 0.9207 μM by BATD-Dma-COF-R. [ABSTRACT FROM AUTHOR]

Electrolytes containing multiple redox couples are promising for improving the energy density of flow batteries. Here, two chelated chromium complexes that are structural isomers are characterized and combined to generate electrolytes containing up to 2 M of active species, corresponding to 53.6 Ah L−1. The mixed isomer approach enables a significantly higher active material content than the individual materials would allow, affording energy dense cells with Coulombic efficiencies of ≥99.6% at 100 mA cm−2 and an open circuit voltage of 1.65 V at 50% state-of-charge. This high concentration, however, comes with a caveat; at a given concentration, an equimolar mixed electrolyte leads to lower voltage efficiency compared to using the individual isomers, while Coulombic efficiency remains constant. Our work demonstrates that exploiting structural isomerism is an efficient approach to improve capacity, but active materials must be selected carefully in mixed systems as differences in operating potentials negatively affect energy efficiency. [ABSTRACT FROM AUTHOR]

Optimized structural support widely affects the improvement of interface structure, promoting the quantity and quality of active species simultaneously for Lithium battery cathodes. Herein, a highly dispersed and anchored active species at the interface of the Zr/CeO2(111) are achieved and are used for advanced Li‐CO2 batteries cathodes. Benefiting from the abundant Ru‐O‐Zr/Ce site, the CO2 adsorption and reduction is enhanced by the migration of the electron density in the C═O of CO2 to Ru. The established Li‐CO2 batteries exhibit excellent activity of 21 075 mAh g−1 and outstanding durability of over 167 cycles as well as low overpotential with 1.03 V at a discharge/recharge rate of 100 mA g−1. The executed experiments combined with DFT calculations unveil that the cubic bimetallic oxide supported Ru exhibits optimized electronic structure at the interface compared to the monoclinic or tetragonal monometallic oxide support, promoting the increase of discharge voltage (from ≈2.5 to 2.73 V). Fundamentally, the redistribution of electron density on the active species Ru‐O‐Zr/Ce are intrinsic to above positive change, which are promoted by the synergistic interaction of Zr and Ce. This investigation provides an approach for the advancement of Li‐CO2 batteries catalytic cathodes and for the promotion of "carbon neutral" goals. [ABSTRACT FROM AUTHOR]

Simple reaction procedure, boiling of an equimolar mixture of [Re(Cl)(CO)3(dppv)] (dppv—cis-1,2-bis(diphenylphosphino)-ethene), 2-(2-pyridyl)benzimidazole (pbi), and TlClO4 in o-dichlorobenzene solution, leads to two, chromatographically separable, isomers of [Re(CO)2(dppv)(pbi)] complex. The obtained species, the yellow-emissive [OC-6–54] and the orange-emissive [OC-6–53] isomers, have been identified using FT-IR, 1H NMR, and 31P NMR spectroscopy and their structures confirmed by means of X-ray investigations. According to obtained crystallography results, the investigated isomers differ mainly in the arrangement of the 2-(2-pyridyl)benzimidazole anion in their structures. Diverse arrangement of the dppv and pbi ligand around the central cis-[Re(CO)2]+ core results in well-pronounced changes in luminescence properties of the studied luminophores. According to results from performed DFT and TDA-DFT computations, the [OC-6–54] isomer emission occurs from the intra-ligand excitation localized mainly within the pbi ligand. In contrary to that, the [OC-6–53] isomer emission indicates some metal-to-ligand charge-transfer character associated with the charge transfer from the Re(CO)2(dppv)+ fragment to the pbi ligand. Moreover, both isomers exhibit different character of their emission decays, mono-exponential and bi-exponential for the [OC-6–54] and [OC-6–53] ones, respectively. In the view of obtained DFT/TDA-DFT results, this has been explained by the presence of an additional excited dark state, operative only in the case of the [OC-6–53] isomer and associated with the charge transfer from the Re(CO)2(pbi) fragment to the dppv ligand. [ABSTRACT FROM AUTHOR]

Bifunctional N-donor carboxylate linkers generally afford dia and sql topology coordination networks of general formula ML2 that are based upon the MN2(CO2)2 molecular building block (MBB). Herein, we report on a new N-donor carboxylate linker, β-(3,4-pyridinedicarboximido)propionate (PyImPr), which afforded Cd(PyImPr)2via reaction of PyImPrH with Cd(acetate)2·2H2O. We observed that, depending upon whether Cd(PyImPr)2 was prepared by layering or solvothermal methods, 2D or 3D supramolecular isomers, respectively, of Cd(PyImPr)2 were isolated. Single crystal X-ray diffraction studies revealed that both supramolecular isomers are comprised of the same carboxylate bridged rod building block, RBB. We were interested to determine if the ethylene moiety of PyImPr could enable structural flexibility. Indeed, open-to-closed structural transformations occurred upon solvent removal for both phases, but they were found to be irreversible. A survey of the Cambridge Structural Database (CSD) was conducted to analyse the relative frequency of RBB topologies in related ML2 coordination networks in order to provide insight from a crystal engineering perspective. [ABSTRACT FROM AUTHOR]

Possible isomers of the N-(3,4-dimethylphenyl)-2-[(7-hydroxy-3′,3′-dimethyl-3′H-spiro[chromene-2,1′-isobenzofuran]-8-yl)methylidine]hydrazinocarbothioamide (HL) spiropyran of the 2-oxaindane series and the [ML(H2O)3]+ (M = Mn(II), Fe(II), Co(II)) complexes on its basis are calculated by the quantum chemical DFT (CAM-B3LYP/6-311++G(d,p)) method. It is shown that complexation inverts the relative stability of spiro- and acyclic isomers of L; the acyclic isomer of the ligand is the most stable one among all the complexes for all metals. The effect of ligand structural isomerism on the relative stability of high- and low-spin states of coordination compounds is estimated. [ABSTRACT FROM AUTHOR]

Alzheimer's disease is a neurologic disorder characterized by the accumulation of extracellular deposits of amyloid-β (Aβ) fibrils in the brain of patients. The key etiologic agent in Alzheimer's disease is not known; however oligomeric Aβ appears detrimental to neuronal functions and increases Aβ fibrils deposition. Previous research has shown that curcumin, a phenolic pigment of turmeric, has an effect on Aβ assemblies, although the mechanism remains unclear. In this study, we demonstrate that curcumin disassembles pentameric oligomers made from synthetic Aβ42 peptides (pentameric oAβ42), using atomic force microscopy imaging followed by Gaussian analysis. Since curcumin shows keto-enol structural isomerism (tautomerism), the effect of keto-enol tautomerism on its disassembly was investigated. We have found that curcumin derivatives capable of keto-enol tautomerization also disassemble pentameric oAβ42, while, a curcumin derivative incapable of tautomerization did not affect the integrity of pentameric oAβ42. These experimental findings indicate that keto-enol tautomerism plays an essential role in the disassembly. We propose a mechanism for oAβ42 disassembly by curcumin based on molecular dynamics calculations of the tautomerism. When curcumin and its derivatives bind to the hydrophobic regions of oAβ42, the keto-form changes predominantly to the enol-form; this transition is associated with structural (twisting, planarization and rigidification) and potential energy changes that give curcumin enough force to act as a torsion molecular-spring that eventually disassembles pentameric oAβ42. This proposed mechanism sheds new light on keto-enol tautomerism as a relevant chemical feature for designing such novel therapeutic drugs that target protein aggregation. • AFM and Gaussian analysis quantify the Aβ42 oligomerization and disassembly. • Curcumins capable of keto-enol tautomerism can disassemble pentameric Aβ42 oligomers. • MD analysis supports that tautomerism acts like a spring and disassembles oligomers. [ABSTRACT FROM AUTHOR]

Purely organic room‐temperature phosphorescence (RTP) materials have attracted increasing attention due to their unique photophysical properties and widespread optoelectrical applications, but the pursuit of high quantum yield is still a continual struggle for RTP emission under ambient conditions. Here, a series of novel RTP molecules (26CIM, 246CIM, 24CIM, and 25CIM) are developed on the basis of indole luminophore, in which a carbonyl group bridges indole and chloro‐substituted phenyl group. The structural isomerism is systematically regulated toward enhancing the intramolecular‐space heavy‐atom effect, thus promoting the spin–orbit coupling and intersystem crossing for high RTP efficiency. While rationally modulating the intramolecular‐space heavy‐atom effect, the phosphorescence efficiency is dramatically increased by 16‐fold from 2.9% (24CIM) to 48.9% (26CIM). Basically, the fully occupied chlorine atoms at the positions 2 and 6 can effectively favor the stronger intramolecular H...Cl effect, and the tight lock coupling with anti‐parallel stacking in 26CIM further boosts RTP emission synergistically. The experimental findings along with deeper theoretical insights elucidate the structure–performance relationship clearly, and further suggest a general strategy for rationally constructing high‐efficiency RTP materials. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Organic semiconductors have drawn extensive attention due to their optoelectronic properties and wide applications in organic optoelectronics. In comparison with the popular 1,4,5,8‐naphthalene diimides (1,4,5,8‐NDIs), the angular‐shaped 1,2,5,6‐NDIs have exhibited tunable photophysical properties, self‐assembly behaviors and charge transporting properties. Due to these unique features, 1,2,5,6‐NDIs show great potential for construction of high performance π‐functional materials. In this review, we highlight the recent advances and future prospects of 1,2,5,6‐NDI‐based π‐systems in the field of organic optoelectronics, including molecular design, synthesis, structure‐property relationships as well as the applications in high performance organic field‐effect transistors, organic photovoltaics, perovskite solar cells, and so on. What is the most favorite and original chemistry developed in your research group? Chemistry of π‐functional materials by using naphthalene and azulene as the basic structural units. How do you get into this specific field? Could you please share some experiences with our readers? This comes from my previous research experience, independent thinking and academic exchange & discussion. When I was a PhD student, my research topic focused on p‐type organic semiconductors. Since I independently carried out scientific research, my research interest turned to developing more challenging n‐type organic semiconductors by using core‐expanded 1,4,5,8‐naphthalene diimides (NDIs). Later on, 1,2,5,6‐NDIs as high‐performance organic semiconductors, the topic of this review paper, entered our study perspective based on the concept of isomerism. Also, based on the concept of isomerism and academic discussion, azulene, the isomer of naphthalene with unique chemical structure and physicochemical properties, became the dominant building block for constructing novel π‐functional materials in my group. How do you supervise your students? Select a research topic with scientific significance and certain challenges, let students consult and intensively read relevant literatures and obtain research inspiration, basic knowledge, experimental skills, writing skills, etc. Encourage students to think independently, try more, and pay more attention to communication and cooperation. Fully train students to write research papers independently. The last but not the least, advocate the academic spirit of being innovative, pursuing excellence as well as rigorous scholarship. What is the most important personality for scientific research? Curiosity and perseverance. What are your hobbies? Reading and walking. If you have anything else to tell our readers, please feel free to do so. No one can imprison your mind and hold your hand to prevent you from doing research work, follow your heart to do what you like and different from others. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Organic semiconductors have drawn extensive attention due to their optoelectronic properties and wide applications in organic optoelectronics. In comparison with the popular 1,4,5,8‐naphthalene diimides (1,4,5,8‐NDIs), the angular‐shaped 1,2,5,6‐NDIs have exhibited tunable photophysical properties, self‐assembly behaviors and charge transporting properties. Due to these unique features, 1,2,5,6‐NDIs show great potential for construction of high performance π‐functional materials. In this review, we highlight the recent advances and future prospects of 1,2,5,6‐NDI‐based π‐systems in the field of organic optoelectronics, including molecular design, synthesis, structure‐property relationships as well as the applications in high performance organic field‐effect transistors, organic photovoltaics, perovskite solar cells, and so on. What is the most favorite and original chemistry developed in your research group? Chemistry of π‐functional materials by using naphthalene and azulene as the basic structural units. How do you get into this specific field? Could you please share some experiences with our readers? This comes from my previous research experience, independent thinking and academic exchange & discussion. When I was a PhD student, my research topic focused on p‐type organic semiconductors. Since I independently carried out scientific research, my research interest turned to developing more challenging n‐type organic semiconductors by using core‐expanded 1,4,5,8‐naphthalene diimides (NDIs). Later on, 1,2,5,6‐NDIs as high‐performance organic semiconductors, the topic of this review paper, entered our study perspective based on the concept of isomerism. Also, based on the concept of isomerism and academic discussion, azulene, the isomer of naphthalene with unique chemical structure and physicochemical properties, became the dominant building block for constructing novel π‐functional materials in my group. How do you supervise your students? Select a research topic with scientific significance and certain challenges, let students consult and intensively read relevant literatures and obtain research inspiration, basic knowledge, experimental skills, writing skills, etc. Encourage students to think independently, try more, and pay more attention to communication and cooperation. Fully train students to write research papers independently. The last but not the least, advocate the academic spirit of being innovative, pursuing excellence as well as rigorous scholarship. What is the most important personality for scientific research? Curiosity and perseverance. What are your hobbies? Reading and walking. If you have anything else to tell our readers, please feel free to do so. No one can imprison your mind and hold your hand to prevent you from doing research work, follow your heart to do what you like and different from others. [ABSTRACT FROM AUTHOR]

Understanding the excited state behavior of isomeric structures of thiolate-protected gold nanoclusters is still a challenging task. In this paper, based on grand unified model and ring model for describing thiolate-protected gold nanoclusters, we have predicted four isomers of Au24(SR)16 nanoclusters. Density functional theory calculations show that the total energy of one of the predicted isomers is 0.1 eV lower in energy than previously crystallized isomer. The nonradiative relaxation dynamics simulations of Au24(SH)16 isomers are performed to reveal the effects of structural isomerism on relaxation process of the lowest energy states, in which that most of the low-excited states consist of core states. In addition, crystallized isomer possesses the shorter e–h recombination time, whereas the most stable isomer has the longer recombination time, which may be attributed to the synergistic effect of nonadiabatic coupling and decoherence time. Our results could provide practical guidance to predict new gold nanoclusters for future experimental synthesis, and stimulate the exploration of atomic structures of same sized gold nanoclusters for photovoltaic and optoelectronic devices. [ABSTRACT FROM AUTHOR]

2,5-furandicarboxylic acid is an extremely appealing renewable chemical building block because of its potential to replace the petrochemical and industrially widespread terephthalic acid via the synthesis of poly(alkylene 2,5-furanoate)s (2,5-PAF). The recent interest in its structural isomer, 2,4-furandicarboxylic acid (2,4-FDCA), opened the study of poly(alkylene 2,4-furanoate)s (2,4-PAF). In this work, 2,4-FDCA was polymerized with linear glycols of increasing chain length, via a solvent-free polycondensation reaction, obtaining high molecular weight 2,4-PAF. Namely, poly(trimethylene 2,4-furanoate) (2,4-PTF), poly(pentamethylene 2,4-furanoate) (2,4-PPeF) and poly(hexamethylene 2,4-furanoate) (2,4-PHF). These polyesters were compression molded into films and subjected to NMR, GPC, WAXS, PLOM, TGA and DSC analyses. The functional properties for food packaging applications were evaluated by mechanical and gas permeability tests. 2,4-PAF had tunable mechanical properties, depending on the glycol used, and in some cases, the mechanical behavior of a thermoplastic elastomer and shape recovery after break. In particular, 2,4-PPeF had outstanding gas barrier properties, while DSC analyses on 2,4-PHF showed an endothermic phenomenon attributed to the isotropization of a partially-ordered phase: it was possible to demonstrate that this phase was disrupted during tensile tests and slowly recovered over time, at room temperature. Overall, the results offer new insights into the structure-property relationships of poly(alkylene 2,4-furanoate)s and display their great potential for the production of biobased, monomaterial, easily recyclable and sustainable food packaging. [Display omitted] • Green synthesis of high molecular weight 2,4-FDCA-based polyesters. • Functional properties suitable for sustainable food packaging. • Isomerism-properties relationship. [ABSTRACT FROM AUTHOR]

This work investigates the critical factors impacting electrochemical CO2 reduction reaction (CO2RR) using atomically precise Au nanoclusters (NCs) as electrocatalysts. First, the influence of size on CO2RR is studied by precisely controlling NC size in the 1–2.5 nm regime. We find that the electrocatalytic CO partial current density increases for smaller NCs, but the CO Faradaic efficiency (FE) is not directly associated with the NC size. This indicates that the surface‐to‐volume ratio, i.e. the population of active sites, is the dominant factor for determining the catalytic activity, but the selectivity is not directly impacted by size. Second, we compare the CO2RR performance of Au38 isomers (Au38Q and Au38T) to reveal that structural rearrangement of identical size NCs can lead to significant changes in both CO2RR activity and selectivity. Au38Q shows higher activity and selectivity towards CO than Au38T, and density functional theory (DFT) calculations reveal that the average formation energy of the key *COOH intermediate on the proposed active sites is significantly lower on Au38Q than Au38T. These results demonstrate how the structural isomerism can impact stabilization of reaction intermediates as well as the overall CO2RR performance of identical size Au NCs. Overall, this work provides important structure–property relationships for tailoring the NCs for CO2RR. [ABSTRACT FROM AUTHOR]

When new covalent organic frameworks (COFs) are designed, the main efforts are typically focused on selecting specific building blocks with certain geometries and properties to control the structure and function of the final COFs. The nature of the linkage (imine, boroxine, vinyl, etc.) between these building blocks naturally also defines their properties. However, besides the linkage type, the orientation, i.e., the constitutional isomerism of these linkages, has rarely been considered so far as an essential aspect. In this work, three pairs of constitutionally isomeric imine-linked donor-acceptor (D-A) COFs are synthesized, which are different in the orientation of the imine bonds (D-C=N-A (DCNA) and D-N=C-A (DNCA)). The constitutional isomers show substantial differences in their photophysical properties and consequently in their photocatalytic performance. Indeed, all DCNA COFs show enhanced photocatalytic H2 evolution performance than the corresponding DNCA COFs. Besides the imine COFs shown here, it can be concluded that the proposed concept of constitutional isomerism of linkages in COFs is quite universal and should be considered when designing and tuning the properties of COFs. Systematic investigation of isomerism in covalent organic frameworks (COFs) can provide key insights into their properties. Here, the authors reveal that the constitutional isomerism of the linkage i.e., linkage orientations distinctly impact COFs' structural and photophysical properties. [ABSTRACT FROM AUTHOR]

Highly active and stable cathodes are critical for aqueous Zn–organic batteries with high capacity, fast redox kinetics, and long life. We herein report para‐, meta‐, and ortho‐dinitrobenzene (p‐, m‐, and o‐DB) containing two successive two‐electron processes, as cathode materials to boost the battery performance. Theoretical and experimental studies reveal that nitro constitutional isomerism is key to zincophilic activity and redox kinetics. p‐DB hosted in carbon nanoflower harvests a high capacity of 402 mAh g−1 and a superior stability up to 25 000 cycles at 5 A g−1, giving a Zn–organic battery with a high energy density of 230 Wh kg−1. An anionic co‐insertion charge storage mechanism is proposed, entailing a two‐step (de)coordination of Zn(CF3SO3)+ with nitro oxygen. Besides, dinitrobenzene can be electrochemically optimized by side group regulation via implanting electron‐withdrawing motifs. This work opens a new window to design multielectron nitroaromatics for Zn–organic batteries. [ABSTRACT FROM AUTHOR]

A modular approach to azulene building blocks was developed starting from readily available aryl‐substituted cyclopentadiene and ortho‐haloaryl aldehyde by dehydration condensation followed by palladium‐catalyzed C−H coupling. It facilitates the synthesis of four nonalternant isomers of pentacene and hexacene, namely, dibenzo[e,g]azulene, benzo[1,2‐f : 5,4‐f′]diazulene, benzo[1,2‐f : 4,5‐f′]diazulene, and naphtho[2,3‐f : 6,7‐f′]diazulene, which exhibit narrow band gaps with high stability in addition to protonation‐caused enhanced near‐infrared fluorescence. We discovered that in these isomers, i) constitutional isomerism influences significantly their photoelectric properties and ii) the elongation of the conjugation system does not necessarily lead to a narrowing in the band gap. Due to the easy modifiability of the nonazulene building blocks, this strategy can be extended to modularly prepare numerous multiazulene‐fused aromatics. [ABSTRACT FROM AUTHOR]

A novel carbazole-bearing diamine (3,6-CPDA) has been synthesized by Suzuki coupling reaction, which is an isomer of our previously reported diamine 2,7-CPDA. In comparison with 2,7-CPDA, the substituted positions of p-aniline in carbazole ring are changed from 2,7-position to 3,6-position for 3,6-CPDA. The two diamine monomers reacted with pyromellitic dianhydride (PMDA) to obtain two isomeric polyimides (3,6-CPPI and 2,7-CPPI). The influence of structural isomerism on the aggregate structure and barrier performance of polyimides was analyzed by X-ray diffractogram, positron annihilation test and molecular simulation. The results show that 3,6-CPPI has relatively twisted chain structure compared with 2,7-CPPI, which hampers the close chains packing and thereby facilitates the formation of large and more free volumes in 3,6-CPPI. In addition, 3,6-CPPI has higher local chain motion than 2,7-CPPI. The high free volume and chain motion improve the gas solubility and diffusivity in 3,6-CPPI, which leads to a reduced gas barrier of 3,6-CPPI in comparison with 2,7-CPPI. This study is helpful to the structural design and preparation of high-barrier polymers. [ABSTRACT FROM AUTHOR]

Exciton interactions are not only observed in assembled molecules but also in compounds with multiple chromophores referred to as superchromophores. We have developed isomeric bis‐squaraine dyes as superchromophores in which two squaraine chromophores are fused onto the isomeric benzodipyrrole skeleton so as to regulate conformations and to reduce distances between two chromophores. The dyes with benzo[1,2‐b:3,4‐b']dipyrrole and benzo[1,2‐b:5,4‐b']dipyrrole moieties exhibited split electronic absorption originated from the intramolecular exciton interaction. The intensity of the split absorption bands varies in correlation with the orientation of chromophores. The isomeric dye with benzo[1,2‐b:4,5‐b']dipyrrole moiety exhibited a near‐infrared absorption associated with the resonance throughout two chromophores. Their electrochemical and spectroelectrochemical properties are distinct from those of monomeric dyes owing to electronic interactions between the two chromophores. Thus, the structural isomerism of the central skeleton significantly affects their optical properties as well as their electrochemical properties. [ABSTRACT FROM AUTHOR]

In this study, mono- and bis-vanillinato-ferrocenyldispirophosphazenes and their Schiff-bases were obtained to investigate the optical and structural properties of cyclotriphosphazenes with stereogenic P-atoms. Accordingly, substitution reactions of two equimolar amounts of the potassium salt of 4-hydroxy-3-methoxybenzaldehyde (potassium vanillinate; KOAr) with one equimolar dichloro trans- (1 and 2) and cis-ferrocenyldispirocyclotriphosphazenes (3 and 4) yielded bis-vanillinato trans- (5 and 6) and cis-dispirocyclotriphosphazenes (8 and 9), respectively. In contrast, using equimolar amounts of trans- (2) and cis-dispirocyclotriphosphazenes (4) with an equimolar amount of KOAr produced the corresponding mono-vanillinato ferrocenyldispirocyclotriphosphazenes, 7 and 10. In addition, condensation reactions of bis-vanillinato trans/cis-dispirophosphazenes (5, 6, 8 and 9) and 1,4-diaminobutane gave rise to novel macrocyclic phosphazene Schiff bases, 11, 12, 13 and 14. The characterization of macrocyclic Schiff bases via1H, 13C and 31P NMR spectroscopy showed that they were present in solution as a mixture of ZZ (syn–syn), ZE (syn–anti) and EE (anti–anti) isomers. The molecular and crystal structures of bis-vanillinato trans- (6) and cis- (9), and mono-vanillinato cis-dispirophosphazenes (10) were elucidated using the X-ray diffraction technique and their absolute configurations were determined as RR, SR and RS, respectively. All dispirophosphazenes have two stereogenic P-atoms, except 10. In addition to two stereogenic P-atoms, mono-vanillinato phosphazene (10) also has a pseudo-asymmetric P-center. Compound 10 was proven to be chiral using the CSA-added 31P NMR spectrum. [ABSTRACT FROM AUTHOR]

• Determining the solubility of SLC in PG + 2-propanol and NMP + water at 293.15–313.15 K. • Studying the solubilization power of various mono-solvents. • Identifying the effect of structural isomerism of propanol on the solubility of SLC. • Developing the general models for SLC solubility in different binary solvents. • Investigating the apparent thermodynamic parameters of the dissolution process. For identifying the solubilization power of aqueous and non-aqueous solvent mixtures for sildenafil citrate (SLC), its solubility was determined in four mono-solvents of propylene glycol, 2-propanol, N-methyl pyrrolidone and water along with the binary solvent mixtures of propylene glycol + 2-propanol and N-methyl pyrrolidone + water at 293.2 to 313.2 K and at pressure of 85 kPa. Among the neat organic solvents and also water, N-methyl pyrrolidone presented a high solubilization power for SLC (8.66 × 10-2 at 313.2 K) and its aqueous binary mixtures had also a more ability to solubilize the drug in compared with the binary (propylene glycol + 2-propanol) mixtures (with the highest value of 4.96 × 10–4 at 313.2 K). Besides, increasing the solubility of SLC with raising temperature illustrated that its dissolution in the aforementioned mixtures was endothermic. The equilibrium solid phase crystal of SLC was also characterized with X-ray powder diffraction analysis to identify no polymorphic transformation, solvate formation or crystal transition during the whole solvent crystallization process. Moreover, the experimental mole fractions were modelled by used commonly cosolvency models and regressed the model parameters. The back-calculated mole fractions of SLC by cosolvency models shown a better agreement with the experimental data (overall mean percentage deviation (OMPD) ≤ 7.6 %) and Jouyban-Acree model as a function of temperature and solvent compositions had the best performance (MPD of 3.2 %). Furthermore, the solubility data sets of SLC in 7 binary solvent mixtures were collected from the literature and correlated with the Jouyban-Acree model and its derivates, the OMPD s for the back-computed solubility indicating the generally trained models, especially Jouyban-Acree-Abraham model (MPD of 24.2 %), had an acceptable ability in the prediction of SLC solubility and can be useful in the pharmaceutical industry. Finally, apparent thermodynamic properties of Gibbs free energy, standard enthalpy and entropy of the dissolution processes were also investigated. [ABSTRACT FROM AUTHOR]

Hydrogen bonding in polyurethane (PU) is imposed by molecular parameters. In this study, the effect of structural isomerism of certain monomers on hydrogen bonding of waterborne polyurethane (WBPU) was studied theoretically and experimentally. Two dihydroxybenzene (DHB)-based structural isomers such as catechol (CC) and hydroquinone (HQ), with different OH positions on the inner benzene core, had been used. Two series of WBPU dispersions were prepared using CC and HQ with defined contents. The binding energies between the catechol (CC)/hydroquinone (HQ) (respective OH group) and urethane/urea were calculated theoretically. By using a density functional theory (DFT) method, it was found that the largest binding energy between the urea and CC was higher than that of urea and HQ. The FT-IR analysis of synthesized polymer was also carried out to compare the results with the theoretical values. The CC-based polymers showed a stronger hydrogen bond both theoretically and experimentally than those for HQ-based polymers. The higher level of hydrogen bond was reflected in their properties of CC-based polymers. The adhesive strength, thermal stability, and hydrophobicity were higher for CC-based materials than those for HQ-based materials. The adhesive strength was increased 25% with the addition of 2.0 wt% CC content. This adhesive strength slightly deviated at a moderately high temperature of 80 °C. [ABSTRACT FROM AUTHOR]

[Display omitted] Calculations using the DFT B3LYP/6-311+G(df,2p) and wb97XD/6-311+G(df,2p) methods predict the stability of a new three-dimensional aromatic organoboron species based on the CB 6 unit. Derived systems containing carbon atoms in two hypercoordination states (planar hexacoordination and inverted-umbrella heptacoordination) can be used as building blocks for constructing various stable condensed systems with many hypercoordinated carbon centers. [ABSTRACT FROM AUTHOR]

Tuning diradical character is an important topic for organic diradicaloids. Herein, we report the precise borylation enabling structural isomerism as an effective strategy to modulate diradical character and thereby properties of organic diradicaloids. We synthesized a new B‐containing polycyclic hydrocarbon that has the indeno[1,2‐b]fluorene π‐skeleton with the β‐carbons bonding to two boron atoms. Detailed theoretical and experimental results show that this bonding pattern leads to its distinctive electronic structures and properties in comparison to that of its isomeric molecule. This molecule has the efficient conjugation between boron atoms and π‐skeleton, resulting in downshifted LUMO and HOMO levels. Moreover, it exhibits smaller diradical character and thereby inhibited diradical properties, such as significantly blue‐shifted light absorption, larger energy bandgap and weak para‐magnetic resonance. Notably, this B‐containing polycyclic hydrocarbon possesses much stronger Lewis acidity and its Lewis acid‐base adducts display enhanced diradical character, demonstrating the positive effects of Lewis coordination on modulating diradical performance. [ABSTRACT FROM AUTHOR]

Endohedral Zintl clusters—multi-metallic anionic molecules in which a d-block or f-block metal atom is enclosed by p-block (semi)metal atoms—are very topical in contemporary inorganic chemistry. Not only do they provide insight into the embryonic states of intermetallic compounds and show promise in catalytic applications, they also shed light on the nature of chemical bonding between metal atoms. Over the past two decades, a plethora of endohedral Zintl clusters have been synthesized, revealing a fascinating diversity of molecular architectures. Many different perspectives on the bonding in them have emerged in the literature, sometimes complementary and sometimes conflicting, and there has been no concerted effort to classify the entire family based on a small number of unifying principles. A closer look, however, reveals distinct patterns in structure and bonding that reflect the extent to which valence electrons are shared between the endohedral atom and the cluster shell. We show that there is a much more uniform relationship between the total valence electron count and the structure and bonding patterns of these clusters than previously anticipated. All of the p-block (semi)metal shells can be placed on a ladder of total valence electron count that ranges between 4n +2 (closo deltahedra), 5n (closed, three-bonded polyhedra) and 6n (crown-like structures). Although some structural isomerism can occur for a given electron count, the presence of a central metal cation imposes a preference for rather regular and approximately spherical structures which maximise electrostatic interactions between the metal and the shell. In cases where the endohedral metal has relatively accessible valence electrons (from the d or f shells), it can also contribute its valence electrons to the total electron count of the cluster shell, raising the effective electron count and often altering the structural preferences. The electronic situation in any given cluster is considered from different perspectives, some more physical and some more chemical, in a way that highlights the important point that, in the end, they explain the same situation. This article provides a unifying perspective of bonding that captures the structural diversity across this diverse family of multimetallic clusters. [ABSTRACT FROM AUTHOR]

Fused‐ring acceptors based on an electron‐deficient core, such as Y6, have become a successful strategy in bulk heterojunction (BHJ) organic solar cells (OSCs) for high power conversion efficiencies (PCEs). Here, five fused‐ring electron acceptors (Y9, Y9‐2F, Y9‐2Cl, i‐Y9‐2F, i‐Y9‐2Cl) are synthesized using fused dithienothiophen[3,2‐b]pyrrolobenzotriazole and halogenated 1,1‐dicyanomethylene‐3‐indanone (IC) to investigate the effect of end‐group (EG) halogenation and structural isomerism on BHJ photovoltaic performance. Due to the strong electronegativity of halogens, all the acceptors with halogenated terminal units possess redshifted absorption spectra and deeper frontier energy levels compared with Y9. Different from asymmetric molecules i‐Y9‐2F and i‐Y9‐2Cl, Y9‐2F and Y9‐2Cl exhibit slightly lower bandgaps. Moreover, the devices based on fluorinated acceptors show more efficient charge collection, obtaining relatively high short‐circuit current density (J sc) and fill factor (FF). The lowest unoccupied molecular orbital energy levels of halogenated acceptors are similar. As a result, OSCs based on poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b′]dithio‐phene))‐alt‐(5,5‐ (1′,3′‐di‐2‐thienyl‐5′,7′‐bis(2‐ethyl‐hexyl) benzo[1′,2′‐c:4′,5′‐c′]dithiophene‐4,8‐dione))] (PBDB‐T):Y9‐2F obtain more balanced J sc and open‐circuit voltage (V oc), and thus an optimal PCE of 15.49% is demonstrated with a V oc of 0.84 V, J sc of 26.30 mA cm−2, and FF of 70.05%.

The purpose of the study was to determine the perceptions that senior high school (SHS) chemistry students, and teachers have about organic chemistry as well as to compare organic chemistry topics that are difficult for students and teachers. Simple random sampling (lottery) and purposive sampling methods were used to select a sample of 100 SHS students who studied elective chemistry and ten chemistry teachers. The research instruments used to collect data for this study were the "organic chemistry perceptions questionnaire for students" and "organic chemistry perceptions questionnaire for teachers." Descriptive statistics (frequencies and percentages) were used to analyze the data collected. The findings revealed that these SHS students have a fairly positive perception of organic chemistry while their teachers had a highly positive perception of organic chemistry. Preparation and chemical reactions of alkenes, preparation and chemical reactions of alkynes, structure and stability of benzene, reactions of benzene, comparison of reactions of benzene and alkenes, petroleum, polymers and naming of alkanes, and structural isomerism were perceived by students as difficult to understand. The rest of the Ghanaian SHS organic chemistry topics (26 out of 34 topics) were perceived as easy to understand by students. Furthermore, the teachers perceived all the SHS organic chemistry topics as easy to teach with the exception of reactions of benzene. The insights gained about teachers' and students' perceived difficult organic chemistry topics in this study imply that teachers' perceptions and how these are communicated to students can have significant effects on learning. The authors believe that both teachers and learners could benefit from this increased awareness of perceptions about difficulties in teaching and learning organic chemistry. They therefore suggest that further studies into how teachers' perceptions influence their teaching and consequently their students' experiences are carried out. In addition, in future research, a diagnostic test based on the topics in the SHS organic chemistry syllabus could be added to ascertain whether the perceived difficult topics are actually difficult for students to answer questions on. This would help teachers to separate perceived difficulties from the actual difficulties (realities) and be able to address them in their lessons. [ABSTRACT FROM AUTHOR]

• Four novel Cu(I)-based MOFs have been synthesized by in-situ reduction of Cu(II) chloride. • Cu(I)-MOFs containing macrometallacyclic with [CuCl] n cluster of μ 2 -, μ 3 - or μ 4 Cl bridge. • Cu(I)-MOFs could be used for detecting nitroaromatic explosives and the best sensing on TNP. Four novel Cu(I)-based metal-organic frameworks, [Cu 3 (p -IPIB)(CN)Cl 2 ] n (Cu(I)-MOF-7), [Cu 3 (p -IPIB)(CN)Cl 2 ] n (Cu(I)-MOF-8), [Cu 3 (p -IPIB)Cl 3 ] n (Cu(I)-MOF-9) and [Cu 2 (p -IPIB-Cl) 1/2 Cl 2 (H 2 O)] n (Cu(I)-MOF-10) where ligand p -IPIB is 1,4-bis[(2-(4-(1H- imidazol -1- yl)- phenyl)-1H- imidazole -1- yl)- methyl ]-benzene, have been successfully synthesized by in-situ reduction of Cu(II) under solvothermal reaction condition. Single X-ray diffraction analysis shown that Cu(I)-MOF-7 and 8 are not only structural supramolecular isomerism containing cyano-bridge which was in situ obtained from the cleavage of the C CN bond of acetonitrile solvent, but also a 3D twofold interpenetration metallo-supramolecular assembly for Cu(I)-MOF-7 and a 3D porous supramolecular assembly containing the macrometallacyclic box structure for Cu(I)-MOF-8 , respectively. Cu(I)-MOF-9 is a 1D channel polymeric chain motif with macrometallacyclic structure containing [Cu 3 Cl 3 ] cluster of μ 3 - and μ 2 -chloride bridge. And Cu(I)-MOF-10 is also a 3D twofold interpenetration metallo-supramolecular assembly with [Cu 4 Cl 3 (H 2 O) 2 ] cluster of μ 4 -chloride bridge. They are thermally stable and exhibit apparent porous properties with adsorption of N 2 and CO 2 gas. The fluorescence sensing experiment indicated that Cu(I)-MOF 7–10 can be used for detecting nitroaromatic explosives through fluorescence quenching in the solution and they have the best sensing effects on the detection of 2,4,6-Trinitrophenol (TNP). Especially, Cu(I)-MOF-9 has the best sensing property towards TNP with a higher quenching constant of 4.53 × 104 L/mol and a lower detection limit of 1.21 ppm. Four novel Cu(I)-based MOFs have been synthesized by in-situ reduction of Cu(II) chloride. They are metallo-supramolecular assemblies with [CuCl] n cluster of μ 2 -, μ 3 - or μ 4 Cl bridge, respectively. Cu(I)-MOFs can be used as fluorescent sensor for detecting nitroaromatic explosives and the best sensing on TNP. [Display omitted] [ABSTRACT FROM AUTHOR]

Herein, two azo-bridged porphyrin dimers were synthesized via Sonogashira and Suzuki coupling reactions. The relationship between molecular structures and electronic structures was investigated by spectroscopic and electrochemical characterizations. In addition, the light-induced structural isomerism of lipophilic azo-Bridged porphyrin dimer could be controlled via steric hindrance modulated functional linkers, and it can only be succeeded in the case of expanded azo-bridged porphyrin dimer. • Two azo-bridged porphyrin dimers were synthesized via Sonogashira and Suzuki coupling reactions. • The relationship between molecular structures and electronic structures was investigated by spectroscopy and electrochemistry. • The light-induced structural isomerism could be controlled via steric hindrance modulated functional linkers. [ABSTRACT FROM AUTHOR]

The existence of isomerism in coordination polymeric structures offers opportunities to understand structure–function relationships. Herein the serendipitous isolation is reported of two isomeric double-pillared-layer coordination polymeric structures arising from two different types of carboxylate bonding of benzene-1,4-dicarboxylate ligands to zinc(II), which constitutes a new type of structural isomerism. The different bonding modes not only alter the shape and size of the pores, but also the nature of interpenetration and photoreactivity. Although two trans,cis,trans-bpeb ligands with conjugated olefin bonds are aligned in close proximity in both of the structures, one isomer undergoes a double [2 + 2] cycloaddition reaction and the second isomer only offers an incomplete single cycloaddition product. This work demonstrates how small changes in the structural connectivity can have an impact on the overall structural, physical and chemical properties of such materials.

Ultralong organic phosphorescence (UOP) has attracted increasing attention due to its potential applications in optoelectronics, bioelectronics, and security protection. However, achieving UOP with high quantum efficiency (QE) over 20 % is still full of challenges due to intersystem crossing (ISC) and fast non‐radiative transitions in organic molecules. Here, we present a novel strategy to enhance the QE of UOP materials by modulating intramolecular halogen bonding via structural isomerism. The QE of CzS2Br reaches up to 52.10 %, which is the highest afterglow efficiency reported so far. The crucial reason for the extraordinary QE is intramolecular halogen bonding, which can not only effectively enhance ISC by promoting spin–orbit coupling, but also greatly confine motions of excited molecules to restrict non‐radiative pathways. This work provides a reasonable strategy to develop highly efficient UOP materials for practical applications. [ABSTRACT FROM AUTHOR]

Further improvement and stabilization of perovskite solar cell (PSC) performance are essential to achieve the commercial viability of next-generation photovoltaics. Considering the benefits of fluorination to conjugated materials for energy levels, hydrophobicity, and noncovalent interactions, two fluorinated isomeric analogs of the well-known hole-transporting material (HTM) Spiro-OMeTAD are developed and used as HTMs in PSCs. The structure–property relationship induced by constitutional isomerism is investigated through experimental, atomistic, and theoretical analyses, and the fabricated PSCs feature high efficiency up to 24.82% (certified at 24.64% with 0.3-volt voltage loss), along with long-term stability in wet conditions without encapsulation (87% efficiency retention after 500 hours). We also achieve an efficiency of 22.31% in the large-area cell. [ABSTRACT FROM AUTHOR]

A series of novel isomeric nickel Schiff base complexes, as well as nickel complexes of related ligands having asymmetric structures have been prepared and characterised using microanalysis, 1H and 13C NMR spectroscopy and ESI-MS. The Schiff base ligands were prepared by condensation reactions involving ethylenediamine and different derivatives of benzophenone. The solid-state structures of eight of the complexes were also determined and revealed that each possessed a regular square planar coordination geometry around the metal ion. Many of the new complexes featured at least one, and in many instances two, protonatable pendant groups that enhance aqueous solubility. This enabled the DNA binding properties of the latter complexes to be explored using a variety of instrumental approaches, including ESI-MS, circular dichroism (CD) spectroscopy, FRET melting assays and FID assays, as well as molecular docking studies. The results of experiments performed using ESI-MS suggested that none of the nickel complexes exhibit a high affinity towards either a double stranded DNA (dsDNA) molecule D2, or the parallel unimolecular quadruplex DNA (qDNA) molecule Q1. In contrast, complexes (8) and (12) both gave spectra which reflected a significant level of binding to the parallel tetramolecular qDNA Q4. The results of binding experiments performed using CD spectroscopy suggested that (12) exhibits a significant level of affinity towards most types of DNA, while (4) shows a preference for interacting with parallel, unimolecular qDNA molecules. Complex (4) produced the lowest values of DC50 in FID assays performed using parallel Q1 or Q4, confirming its affinity for these qDNA molecules. The results of FRET melting experiments provided further evidence that (12), along with (8), can interact extensively with anti-parallel unimolecular qDNA. Experiments which monitored the effect of the nickel complexes on the melting temperature of D2 showed that none had a stabilising effect on this dsDNA molecule. [ABSTRACT FROM AUTHOR]

Amino acid transporters, which play a vital role in transporting amino acids for the biosynthesis of mammalian cells, are highly expressed in types of tumors. Increasing studies have shown the feasibility of amino acid transporters as a component of tumortargeting therapy. In this review, we focus on tumor-related amino acid transporters and their potential use in tumor-targeting therapy. Firstly, the expression characteristics of amino acid transporters in cancer and their relationship with tumor growth are reviewed. Secondly, the recognition requirements are discussed, focusing on the "acidbase" properties, conformational isomerism and structural analogues. Finally, recent developments in amino acid transporter-targeting drug delivery strategies are highlighted, including prodrugs and nanocarriers, with special attention to the latest findings of molecular mechanisms and targeting efficiency of transporter-mediated endocytosis. We aim to offer related clues that might lead to valuable tumor-targeting strategies by the utilization of amino acid transporters. [ABSTRACT FROM AUTHOR]

Structural isomerism of the Pd4(L)4(RCO2)4 (L = CO, CH2, NO; R = CC13, CF3, CH3) complexes was studied in the framework of the density functional theory (DFT). Among the Pd4(CO)4(RCO2)4 and Pd4(CH2)4(RCO2)4 complexes the most stable were the isomers with alternate coordination of pairs of carbonyl and carboxylate ligands on the sides of a planar rectangular metal core. The isomers with the pairwise coordination of NO/RCO2 on one side of the metal core are the most stable between the Pd4(NO)4(RCO2)4 complexes. The features of mutual coordination of ligands in polynuclear complexes of palladium are clarified using the obtained results. [ABSTRACT FROM AUTHOR]

Photochromic polymers have attracted a lot of attention in the last few decades because of their useful properties related to color change and optical data storage. In this contribution we present a macromolecular structure influence on the output spectroscopic properties in the manner of all-optical switching and harmonics of light generation. Slight chemical architecture changes make significant difference if we consider generated optical anisotropy magnitude and kinetics of photoinduced process but also force diversified nonlinear optical response. We have placed a strong electron acceptor unit, fluorine atom, in a few alternate substitution patterns. One of them (1,4-) activates the phenyl unit, the other one (1,3-) works opposite. Finally, a joined form was also investigated, which led to appealing results making materials engineering field of studies a useful tool dedicated for advanced functional materials fabrication. Moreover, experimental achievements presented here indicate that investigated materials are perfect candidates for opto-electronics, photonics and spectroscopy fields and can be easily implemented into individual optical processing solutions. [Display omitted] • Synthesis and comprehensive materials analysis of the three novel fluorophotochromic polymers. • Structural isomerism and derivatives vs. high influence on the output spectroscopic features. • Light driven individual nonlinear optics response based on the polymer's structure. • All-optical switching phenomenon. • Higher harmonics of light generation. [ABSTRACT FROM AUTHOR]

A new Zintl cluster, [(Ni@Sn9)In(Ni@Sn9)]5−, has been isolated in two distinct isomeric forms, one where both Ni@Sn9 units are coordinated to the bridging In atom in an η3- mode, the other where one is η3- and the other η4-. Density functional theory indicates that the energetic separation between these two structures is minimal, suggesting that crystal packing plays a decisive role in the structural chemistry. A comparison of the electronic structure of [(Ni@Sn9)In(Ni@Sn9)]5− with [(Ni@Ge9)Ni(Ni@Ge9)]4−, which has four fewer valence electrons, sheds some light on possible mechanisms that lead to the fusion of cluster fragments. [ABSTRACT FROM AUTHOR]

The presented analytical method enabled the Toxicology Department at the Cuyahoga County Medical Examiner's Office to identify 26 and quantitatively report 24 compounds in 500 μL of whole blood, including fentanyl analogues (fentalogues) such as methoxyacetyl fentanyl (MeOAF) and cyclopropyl fentanyl (CPF). This second-generation method (FG2) was developed with the objective to improve the existing analysis (FG1) by decreasing sample size, lowering limits of detection (LOD) and lower limit of quantitation, minimizing ion suppression and resolving chromatographic interferences. Interferences may occur in the analysis of fentanyl, MeOAF, CPF, 3-methylfentanyl (3MF), butyryl fentanyl and isobutyryl fentanyl due to isobars and structural or geometric isomerism with another analogue or metabolite. The isomeric and isobaric fentalogues were grouped into three sets. The LOD established for Set 1 [MeOAF, para -methoxyacetyl fentanyl, para -fluoro acryl fentanyl (isobar), fentanyl carbamate], 2-furanyl fentanyl, Set 2 [CPF, (E)-crotonyl fentanyl] and carfentanil was 0.0125 ng/mL. The LOD established for N -methyl norfentanyl, norfentanyl, norcarfentanil, despropionyl fentanyl (4-ANPP), acetyl fentanyl, β-hydroxy fentanyl, benzyl fentanyl, acryl fentanyl, alfentanil, fentanyl, para -fluoro fentanyl, Set 3 [(±)- trans -3MF, (±)- cis -3MF, isobutyryl and butyryl fentanyl], para -fluoroisobutyryl fentanyl, sufentanil, phenyl fentanyl and cyclopentenyl fentanyl was 0.0625 ng/mL. Seven-point linear calibration curves were established between 0.025 and 4.0 ng/mL for the 8 analytes with the lower LOD and 0.125 and 20 ng/mL for the 18 analytes with the higher LOD. 4-ANPP and cyclopentenyl fentanyl met qualitative reporting criteria only. The results for five postmortem and two driving under the influence of drugs authentic case samples are presented. To the authors' knowledge, FG2 is the first published method that achieved baseline resolution of the nine structural/stereo isomers and one isobar by ultra-high performance liquid chromatography–MS-MS and provided quantitative validation data for nine compounds. FG2 may be used as the new baseline for future isomers that need to be chromatographically separated. [ABSTRACT FROM AUTHOR]

Two isomeric benzodithiophene-fused perylene diimides, BPDI-1 and BPDI-2 , are designed and synthesized via photo-induced ring-closure reaction between perylene diimide (PDI) acceptor and both isomeric benzodithiophene donor cores, including benzo[2,1- b :3,4- b' ]dithiophene (BDP) and benzo[1,2- b :4,3- b' ]dithiophene (BdT). The effect of structural isomerism on the molecular geometry, absorption, energy level, film morphology as well as photovoltaic performance is comparatively studied. It is found that the variation of the S atom substituted position in the donor cores results in distinct molecular geometries for the newly-developed BPDI-1 and BPDI-2 acceptors. Compared with BDP -containing BPDI-1 , the incorporation of BdT core endows BPDI-2 with a remarkably enhanced backbone distortion. When blended with the commercially available polymer donor (PTB7-Th), such twisted structure feature for the BPDI-2 acceptor plays a key role in reducing molecule aggregation, which is helpful for the enhancements of short-circuit current density and photovoltaic efficiency effectively. As a result, non-fullerene solar cells fabricated from BPDI-2 acceptor achieve higher photovoltaic efficiency (4.44%) than that of BPDI-1 (2.98%), mainly benefited from superior short-circuit current density. This work provides us comparative understanding of isomeric geometry and device performance. Image 1 • Two isomeric benzodithiophene-fused PDIs are synthesized for non-fullerene OSCs. • Structural isomerism results in different molecular geometries and optoelectronic properties. • The highest pohotovaltaic efficiency of 4.44% is achieved for the BPDI-2 based OSCs. [ABSTRACT FROM AUTHOR]

Knudsen Effusion Mass Spectrometry (KEMS) was used to find the solid state vapor pressures of a range of atmospherically relevant organic molecules from 298 K to 333 K. The selection of species analyzed allowed for the effect of structural isomerism, specifically positional isomerism, and stereoisomerism, specifically geometric isomerism, on solid state vapor pressure to be investigated. In addition, the effect of varying the number of carboxylic acid groups present within a molecule's structure and of varying alkyl chain length was assessed. The solid state vapor pressures were converted to subcooled liquid vapor pressures using experimental heat of fusion and melting point values. The resulting subcooled liquid vapor pressures were found to be up to 7 orders of magnitude lower than the vapor pressures estimated from models. Some of this variation between experimentally determined subcooled liquid vapor pressures and predicted vapor pressures, which use group contribution methods, can be attributed to the effects of isomerism which are largely not taken into account in models. Whilst these techniques might have both structural and parametric uncertainties, of the compound classes tested, a general inverse relationship between melting point and solid state vapor pressure was observed. Within each compound class the variations in vapor pressure can be attributed to the number and size of functional groups present and the relative positions of those functional groups to each other both positionally and geometrically. These two factors impact upon both the molecules' dipole moments and upon their ability to interact both intramolecularly and intermolecularly via hydrogen bonding, thus explaining the differences in observed vapor pressure. Partitioning calculations using a range of condensed mass loadings show that whilst using vapor pressure values derived from models would put most of the compounds in the vapor phase, using the experimental values obtained here would mean a significant fraction of the organic molecules would be in the condensed phase. This could have a significant impact upon the formation and nature of atmospheric aerosol, and comparisons with ambient data obtained from other mass spectrometry techniques during bonfire night in Manchester in 2016 are made in an attempt to assess this potential atmospheric importance. Copyright © 2019 American Association for Aerosol Research [ABSTRACT FROM AUTHOR]

• Trichlorosilane with different structural isomerism were modified on SiO 2 NPs via a simple one-step reaction. • Superhydrophobic SiO 2 NPs were successfully synthesized (WCA > 150° and SA < 10°). • The effect of the trichlorosilane isomerism was affected by the reaction time. • The superhydrophobic coating showed high transparency. Superhydrophobic (SH) silica (SiO 2) nanoparticles (NPs) were successfully synthesized through a simple and facile technique. The effect of chlorosilane isomers was investigated by the grafting of butyltrichlorosilane (C4But) and dichloro (3-chloropropyl) methylsilane (C4Di) on superhydrophilic SiO 2 NPs. The SEM results displayed that the particle size of C4Di modified SiO 2 (C4Di-SiO 2) NPs was larger than C4But modified SiO 2 (C4But-SiO 2). This can be due to the steric effect of the methyl group on the C4Di segment. The wetting analysis revealed that C4Di-SiO 2 cannot reach SH criteria as it showed a water contact angle (WCA) of 149° and a sliding angle (SA) over 10°, while C4But-SiO 2 showed a SH surface with a WCA of 159° and SA of 2°. Interestingly, the modified SiO 2 NPs created a transparent film on the glass substrate which is a key opportunity for self-cleaning application. [ABSTRACT FROM AUTHOR]

It is a challenge to make clear how isomerism in a heterogeneous catalyst induces distinct differences in catalytic properties, as attainment of the structural isomerism in a conventional catalyst is difficult. By successfully identifying the isomerism in the atomically precise Au nanoclusters, an exciting opportunity for unravelling catalysis of isomeric catalysts is opened up. Herein, we report that the isomerism in the Au28(SR)20 nanoclusters with different surface atom arrangements can indeed render different catalytic behaviors in the selective hydrogenation of CO2. We anticipate that our studies will serve as a starting point for fundamental investigations about how to control the catalytic activity and selectivity by the isomerism‐induced catalysis. [ABSTRACT FROM AUTHOR]