Isomers 1a Research Articles

Geometrically isomeric [Ir(C^N)(C’^N’)(N’’^O)-tris-heteroleptic [Ir(dFppy)(CN-ppz)(pic)] Ir(III)-complexes with blue-light: Forwards to efficient blue organic light-emitting diodes

Despite the great success of Ir(III)-complex-based green/red-light OLEDs (OLED = organic light-emitting diode), the realization of their efficient blue-OLEDs is far behind and challenging. Herein, using HdFppy (2-(2,4-difluorophenyl)pyridine) and CN-ppzH (4-(1H-pyrazol-1-yl)benzonitrile) as the HC^N/HC’^N’ ligands and Hpic (2-picolinic acid) as the N’’^O-ancillary ligand, the [Ir(C^N)(C’^N’)(N’’^O)]-tris-heteroleptic molecular design strategy was adopted, obtaining the two [Ir(dFppy)(CN-ppz)(pic)]-configured blue-emitting (λPL (photoluminescence emission peak) = 466, 496(sh) nm; ΦPL (photoluminescence quantum efficiency) = 0.41–0.46) geometrical isomers 1a and 1b. Further through the doped and vacuum-deposited fabrication, their blue-OLEDs-1A/1B with the LMax (maximum luminance) values up to 18090–22528 cd/m2 and the ηEQEMax (maximum external quantum efficiency) sizes of 7.99–8.42 %, were realized, respectively. This study result shows that [Ir(dFppy)(CN-ppz)(pic)]-included [Ir(C^N)(C’^N’)(N’’^O)]-tris-heteroleptic Ir(III)-complexes can be used as the attractive blue-phosphor candidates forwards to efficient blue-OLEDs.

Facile C[sbnd]H aryl and O[sbnd]H bonds activation at dirhenium site of [Re2(CO)8(THF)2] complex

The activation of small molecules is a topic of great interest and previously we reported on the easy activation of different types of EH bonds at the dinuclear complex [Re2(CO)8(THF)2] (1) where labile THF molecules coordinate to adjacent rhenium(0) atoms. Here we extend the reactivity of 1 reporting on the oxidative addition of benzene and toluene at room temperature to give [Re2(μ-H)(μ-κC-Ar)(CO)8], Ar = −C6H5 (2) and −C6H4Me (3). Compound 3 is a new example of μ-κC-Ar dinuclear rhenium complex and has been obtained as para and meta isomers (3a,b). It is known from the literature that 2 can activate arenes and heteroarenes via reductive elimination of benzene and oxidative addition of CH bonds to the dinuclear fragment. Here we have studied the reaction of 2 with C6D6 and H2CC(H)Ph and determined the kinetic constants by 1H NMR (1.4 × 10−5 s−1 at 308 K and 1.1 × 10−5 s−1 at 298 K, respectively). The results indicate that the rate-determining step of the reaction is the reductive elimination of benzene, while the oxidative addition is fast. Water and methanol react with 1 in toluene at room temperature to give the hydroxo and methoxo hydrido complexes [Re2(μ-H)(μ-OR)(CO)8], RH (5) and CH3 (6). On reacting 1 with water in deuterated toluene, and monitoring by 1H/2H NMR, a preferential deuteration of the hydride site to give [Re2(μ-D)(μ-OH)(CO)8] is evidenced. This finding excludes the oxidative addition of water on the dinuclear “Re2(CO)8” fragment while supporting a heterolytic addition of water via protonation at the µ-κC-tolyl group, elimination of toluene and addition of OH−. Single crystal X-ray diffraction analyses have been performed for complexes 3a, 5 and 6 and their solid state structures have been determined. In particular, the crystal structure of 5 results in a new polymorphic form (5b) and it is discussed in comparison with the already known one (5a).

Chemical constituents of five Saxifraga species and their virucidal activities

The chemical constituents of Saxifraga stolonifera, S. fortunei, S. nipponica, S. cortusifolia, and S. rebunshirensis were investigated for structure and virucidal activity. In addition to the Saxifraga species-derived tannins, 30 compounds (1−30) were isolated from the five species. 5-Hydroxy-4-methoxy-3-O-(6-O-caffeoyl)-β-D-glucopyranosyl benzoic acid (1) and kaempferol 3-O-β-d-xylopyranosyl-(1 → 2)-β-D-xylopyranoside (2) were identified as undescribed compounds. Although 1 was isolated as the (E)-isomer of its caffeoyl moiety, under light it became over time a mixture of the (Z)-isomer (1a) and (E)-isomer (1). Kaempferol 3-O-β-d-xylopyranosyl-(1 → 2)-β-D-glucopyranoside (3) was an analog of 2 and a known compound, whose NMR assignment was reconsidered and described. 6-Isopropyl-5,5-dimethyldihydropyrimidine-2,4(1H,3H)-dione (30) was expected to be a racemic mixture based on its optical rotation and X-ray crystallography data. The virucidal activities of the isolated compounds (1–30) against influenza A virus, severe acute respiratory syndrome coronavirus 2, feline calicivirus, and murine norovirus were evaluated to identify the presence of compounds other than the Saxifraga species-derived tannins, which exhibited virucidal activities. Although the isolated compound activities were relatively weak compared to those of Saxifraga species-derived tannins, the potential virucidal activity of the compounds with galloyl groups was confirmed.

Unraveling biological disparities in configurational isomers of pyrazolyl-dihydrofurans using in vitro, DFT and in silico approach

The biological disparities in the high activity of one isomeric form over another have attracted significant interest from medicinal chemists and opened new avenues for synthesizing pure diastereoisomeric drugs.A series of diastereoisomeric pure pyrazolyl-dihydrofurans (6a-6ae) were synthesized in good to excellent yields, and their structures were determined using NMR, LCMS and X-ray crystallography. The difference in the stability of cis and trans isomers has been established using DFT-based studies. Using the serial dilution method, the developed synthetics were evaluated for their bio-efficacy against bacterial and fungal strains. The cytotoxicity was evaluated against mouse fibroblast cells as well as using the seed germination method.All the reactions proceeded smoothly and resulted into cis as the significant isomer; the stability over trans isomer has been established using DFT-based computational studies. Considering 6a and 7a as prototype, the difference in their biological response has been evaluated through in vitro anti-microbial assay. A significant difference in the biological activity has been observed, as the cis isomer (6a) has been found to be more potent over its respective trans isomer (7a) in bacterial assay. As far as the fungal response is concerned, no difference in their biological activity has been observed. The investigated compounds are non-cytotoxic against mouse fibroblast cells and Brassica nigra seeds. The experimentally determined in vitro results have been established using in silico studies.The cis isomer (6a) with an MIC of 3.25 µg/mL has been found to be more potent than the respective trans (7a) form (MIC = 6.25–12.5 µg/mL) when evaluated against different gram positive and negative strains utilized in the present study. However, no disparity in their biological response has been observed in fungal studies.

Geometrically isomeric [Ir(C^N)(C’^N’)(N’’^N’’’)]-tris-heteroleptic complexes versus [Ir(C^N)2(N’’^N’’’)]-bis-heteroleptic complex: Towards High-performance near-infrared (NIR) polymer light-emitting diodes

Despite efficient NIR-OLEDs/PLEDs fabricated from [Ir(C^N)2(O^O)]/[Ir(C^N)2(N^O)]-bis-heteroleptic and few [Ir(C^N)(C’^N’)(O^O)]/[Ir(C^N)(C’^N’)(N^O)]-tris-heteroleptic iridium(III)-complexes, the problems to dissociation of N^O/O^O-ancillary units upon acid-hydrolysis or pyrolysis, together with geometrically isomeric complexity, have to be faced. Herein, a molecular design strategy to C1-symmetrical [[Ir(C^N)(C’^N’)(N’’^N’’’)]-tris-heteroleptic Ir(III)-complex (HC^N = Hiqbt, HC’^N’ = Hppy and HN’’^N’’’ = Hftrpz) is developed. The improved stability of [Ir(iqbt)(ppy)(ftrpz)] (2) is arisen from the strong HN’’^N’’’-ligand-field strength as compared to the N^O/O^O-ancillary counterparts. Meanwhile, owing to the Hftrpz-induced asymmetry, two geometrical isomers (2a and 2b) of [Ir(iqbt)(ppy)(ftrpz)] are first isolated. Noticeably, using the two isomeric NIR-phosphors [Ir(iqbt)(ppy)(ftrpz)]-a/b (2a and 2b) as the dopants, their high-performance NIR-PLEDs than that with the [Ir(iqbt)2(ftrpz)] (1) counterpart, are realized. Especially the NIR-PLED-2b, exhibits both an attractively high efficiency (ηEQEmax = 5.94 %; λem = 692 nm) and almost negligible (< 5 %) efficiency roll-off. And thus, this finding engenders [Ir(C^N)(C’^N’)(N’’^N’’’)]-tris-heteroleptic Ir(III)-complexes a new platform to the realization of high-performance, low-cost, large-area and scalable NIR-PLEDs.

On the Keto‐Enol‐Tautomerism of 2‐(1‐Hydroxyethylidene)malononitrile and Its Lewis Adduct Formation with B(C6F5)3

Abstract2‐(1‐Hydroxyethylidene)malononitrile (4) is commercially sold as the keto isomer and is described in the literature as either a keto (4 b) or enol (4 a) species. Using NMR techniques and single crystal X‐ray diffraction, we were able to show that 4 exists exclusively as the enol isomer (4 a) in solution as well as in the solid state, which agrees with quantum chemical calculations. By adding one or two equivalents of the Lewis acid B(C6F5)3, the mono‐ or diadducts are formed in exergonic reactions, in which the enol form is further thermodynamically stabilized. The structure and acidity of enol 4 a and its borane adducts are discussed based on experimental and theoretical results.

Gradual solid-state redox-isomerism in the lanthanide series.

Oxidation of [(ArBIG-bian)2-Yb2+(dme)] (1) (ArBIG-bian = 1,2-bis[(2,6-dibenzhydryl-4-methylphenyl)imino]acenaphthene; dme = 1,2-dimethoxyethane) by 0.5 equivalent of Me2NC(S)S-S(S)CNMe2 in dme at ambient temperature affords a mixture of two products, [(ArBIG-bian)2-Yb3+{SC(S)NMe2}1-(dme)] and [(ArBIG-bian)1-Yb2+{SC(S)NMe2}1-(dme)], which represent two redox-isomers (2a and 2b, respectively). Their ratio in solution depends on the solvent as well as on the temperature. In the solid state, a decrease of temperature (350 → 100 K) caused an electron transfer from the Yb2+ ion to the ArBIG-bian radical-anion in isomer 2b to afford isomer 2a. Accordingly, the ratio of isomers 2a and 2b changes from 1 : 1 (350 K) to 3 : 1 (100 K). In contrast, in the dimer [(dme)(dpp-bian)1-Yb2+(μ-Cl)2Yb3+(dpp-bian)2-(dme)] (dpp-bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene), which is the sole example of a lanthanide complex that reveals solid-state redox-isomerism (valence tautomerism) reported so far, the electron transfer from the Yb2+ ion to the dpp-bian radical-anion takes place at around 150 K and is completed within a temperature interval of ca. 7 K.

Bright NIR-Emitting Styryl Pyridinium Dyes with Large Stokes' Shift for Sensing Applications.

Two NIR-emitting donor-π-acceptor (D-π-A) type regioisomeric styryl pyridinium dyes (1a-1b) were synthesized and studied for their photophysical performance and environment sensitivity. The two regioisomers, 1a and 1b, exhibited interesting photophysical properties including, longer wavelength excitation (λex ≈ 530-560 nm), bright near-infrared emission (λem ≈ 690-720 nm), high-fluorescence quantum yields (ϕfl ≈ 0.24-0.72) large Stokes' shift (∆λ ≈ 150-240 nm) and high-environmental sensitivity. Probe's photophysical properties were studied in different environmental conditions such as polarity, viscosity, temperature, and concentration. Probes (1a-1b) exhibited noticeable changes in absorbance, emission and Stokes' shift while responding to the changes in physical environment. Probe 1b exhibited a significant bathochromic shift in optical spectra (∆λ ≈ 20-40 nm) compared to its isomer 1a, due to the regio-effect. Probes (1a-1b) exhibited an excellent ability to visualize bacteria (Bacillus megaterium, Escherichia coli), and yeast (Saccharomyces cerevisiae) via fluorescence microscopy.

Serendipitous discovery of a regioselective synthesis of novel benzoyloxy substituted phenyl/benzyl-sulfanyl/selenylbisesters, 3-benzoyloxy-3-(phenylsulfanyl)-β-lactams and their antimicrobial evaluation

The regioselective benzoyloxylation process involves stirring a mixture of phenyl/benzyl-sulfanyl/selenylethanoate 1a-c with appropriate oxidant [benzoyl peroxide (BPO) 2a/ m-chloroperbenzoic acid (m-CPBA) 2b /bis(p-methoxybenzoyl peroxide) (BPM-BPO) 2c] under catalysis of hydrated copper acetate in toluene at 60 °C/RT. Regioselective C–H functionalization of esters 1a-c leads to benzoyloxy substituted phenyl/benzyl-sulfanyl/selenylbisesters 3a-g in good to excellent yields (80–95%). Variably substituted trans-3-phenylsulfanyl-β-lactams 4 employed for C3-H functionalization with BPO 2a generates diastereoisomeric mixture of trans- and cis-3-benzoyloxy-3-(phenylsulfanyl)-β-lactams 5 and 6 as major and minor isomers after efficient column chromatographic purification. The structural confirmation was done using IR, 1H NMR, 13C NMR, DEPT-90 NMR spectroscopic analysis and CHNS elemental analysis. In vitro antibacterial and antifungal evaluations on bisesters suggest benzylselenyl-bisester 3c as potent antimicrobial agent. Out of trans- and cis-3-benzoyloxy-β-lactams 5a and 6a, the trans isomer 5a was active against all microbial strains whereas the cis isomer 6a was completely inactive.

Five Bonds to Carbon through Tri-Coordination in &#x0D; Al3C3−/0

Here, five bonds to carbon through tri-coordination are theoretically established in the global minimum energy isomers of Al3C3− anion (1a) and Al3C3 neutral (1n) for the first time. Various isomers of Al3C3−/0 are theoretically identified using density functional theory at the PBE0-D3/def2-TZVP level. Chemical bonding features are thoroughly analyzed for these two isomers (1a and 1n) with different bonding and topological quantum chemical tools, such as adaptive natural density partitioning (AdNDP), Wiberg Bond Indices (WBIs), nucleus-independent chemical shifts (NICS), and atoms in molecules (AIM) analyses. The structure of isomer 1a is planar with C2v symmetry, whereas its neutral counterpart 1n is non-planar with C2 symmetry, in which its terminal aluminum atoms are out of the plane. The central allenic carbon atom of isomers 1a and 1n exhibits tri-coordination and thus makes it a case of five bonds to carbon, which is confirmed through their total bond order as observed in WBI. Both the isomers show σ- and π-aromaticity and are predicted with the NICS and AdNDP analyses. Further, the results of ab initio molecular dynamics simulations reveal their kinetic stability at room temperature; thus, they are experimentally viable systems.

RuCl2(DPEphos)(N-N)] (DPEphos = bis[(2-diphenylphosphino)phenyl]ether; N-N = 2-aminomethylpyridine or ethylenediamine): synthesis, characterization and transfer hydrogenation of aryl-ketones

The complexes trans/cis-[RuCl2(DPEphos)(ampy)] (trans – 1a; cis – 1b) and trans/cis-[RuCl2(DPEphos)(en)] (trans – 2a; cis – 2b) were obtained from the reactions of mer-[RuCl2(DPEphos)(PPh3)] (PPh3 = triphenylphosphine) with the corresponding amine in CH2Cl2. The isomer 1a was observed in situ when the reaction was carried out at r.t.; isolation leads to mixtures with 1b, while the latter was isolated when the reaction was performed under reflux. On the other hand, trans-[RuCl2(DPEphos)(en)] (2a) was obtained at r.t., in good yield and the cis-isomer 2b was observed when the reaction was carried out under reflux or when a CH2Cl2 solution of 2a is exposed to ambient light, but 2b was not isolated in pure form even under reflux for one week. Cyclic voltammetry studies revealed the presence of one reversible process with E1/2 0.57 and 0.40 V for 1b and 2a, respectively. Both 1b and 2a were used as pre-catalysts for reduction of acetophenone and p-substituted acetophenones (F–, Me– and MeO–) in transfer-hydrogenation conditions (isopropanol, 82 °C, and pre-catalyst:KOH:acetophenones in molar ratio 1:20:500 and/or 1:20:1000) showing conversions of 93–99% and TOF values up to 4.2 104 h−1.

Design of hydroxyl- and thioether-functionalized iron-platinum dimetallacyclopentenone complexes. Crystal and electronic structures, Hirshfeld and docking analyses and anticancer activity evaluated by in silico simulation

A series of metal-metal bonded iron-platinum heterobimetallic complexes has been prepared by carbon-carbon coupling of [(OC)3Fe(µ-C=O)(µ-dppm)Pt(PPh3)] (1) (dppm = Ph2PCH2PPh2) with the terminal alkynols 4-pentyn-1-ol, 4-pentyn-2-ol and the internal thioether-functionalized alkyne 1,4-bis(p-tolylthio)but-2-yne. The resulting dimetallacyclopentenones [(OC)2Fe(µ-dppm){µ-C(=O)C((CH2)3OH)=CH}Pt(PPh3)] (2a) and [(OC)2Fe(µ-dppm){µ-C(=O)C(CH2CHOHCH3)=CH}Pt(PPh3)] (2b) featuring intramolecular hydrogen O-H···O=C bonding have been structurally characterized, as well as [(OC)2Fe(µ-dppm){µ-C(=O)C(CH2S(p-tolyl))=C(CH2S(p-tolyl))}Pt(PPh3)] (2c). NMR studies reveal that coupling of 1 with HCC-CH2CH2CH2OH yields initially the kinetic isomer [(OC)2Fe(µ-dppm){µ-C(=O)C(H)=C((CH2)3OH)}Pt(PPh3)] (2a’), which upon heating converts quantitatively to the thermodynamic isomer 2a. Furthermore, the molecular structures of series 2 were investigated by means of Hirshfeld surface analyses. As targets for a bioinformatic study, molecular docking studies were applied to the complexes 2 and revealed the occurrence of intermolecular interactions with four different protein residues associated with breast (1hk7 and 3eqm) and prostate cancer (2q7k and 2ax6). According to the docking results, this family of complexes displays better activity on prostate cancer proteins rather than breast cancer ones. The molecular structures of compounds 2 were also optimized using DFT quantum chemical calculations. The large band gap implies low reactivity and good stability of these complexes.

Synthesis and characterization of a series of N,N′‐substituted urea derivatives by using electrospray ionization tandem mass spectrometry: Differentiation of positional isomers

Characterization of N,N'-substituted ureas was found to be challenging by nuclear magnetic resonance (NMR) spectroscopy, particularly N-di- and tri-alkylated ureas because of the absence of adjacent protons. In the present study, electrospray ionization tandem mass spectrometry has been used to differentiate positional isomeric pairs and to characterize a series of N,N'-substituted ureas, as these compounds have significant importance for drug discovery. Additionally, urea is an essential functionality in several bioactive compounds as well as a variety of clinically approved therapies. High-resolution electrospray ionization tandem mass spectrometry (ESI-HR-MS/MS) has been used to characterize a series of N,N'-substituted urea derivatives and differentiate two pairs of positional isomers. The data was acquired by Xcaliber application in positive ionization mode. ESI-HR-MS/MS spectra of [M + H]+ ions of the positional isomeric urea derivatives 8a and 8b show distinct fragmentation patterns. For example, the MS/MS spectrum of the [M + H]+ ion of isomer 8a displays the abundant fragment ion at m/z 285.1595, which was totally absent in isomer 8b. This would be plausibly formed by the cleavage of the C-N bond of the urea group with the elimination of the isocyanate moiety. In contrast, the MS/MS spectrum of the [M + H]+ ion of isomer 8b shows an intense ion at m/z 311.1389 which is completely absent in isomer 8a which would be formed by the cleavage of the C-N bond attached to the ring nitrogen. Similarly, another pair of positional isomers, 8c and 8d, have been clearly distinguished by their fragmentation behaviour. In addition, a series of N,N'-substituted urea derivatives were studied to investigate the impact of different substitution on the fragmentation behaviour. The present study demonstrates that ESI-HR-MS/MS can be used to differentiate pairs of N,N'-substituted urea positional isomers and characterize a series of derivatives. It was observed that a characteristic fragment ion was formed by the C-N bond cleavage with the elimination of an isocyanate moiety. The proposed mechanism of fragmentation was supported by the change in the fragmentation pathway upon alkylation of the NH. In order to generalize this fragmentation pattern, a series of N-alkylated ureas was synthesized and studied by MS/MS.

Total Synthesis of Stemarene and Betaerene Diterpenoids: Divergent Ring-Formation Strategy and Late-Stage C–H Functionalization

A unified protecting group-free approach to two stemarene and two betaerene diterpenoids through a bioinspired two-phase strategy has been developed, and three of them were obtained for the first t...

Prenylated Coumaric Acids from Artemisia scoparia Beneficially Modulate Adipogenesis.

Two new diprenylated coumaric acid isomers (1a and 1b) and two known congeners, capillartemisin A (2) and B (3), were isolated from Artemisia scoparia as bioactive markers using bioactivity-guided HPLC fractionation. Their structures were determined by spectroscopic means, including 1D and 2D NMR methods and LC-MS, with their purity assessed by 1D 1H pure shift qNMR spectroscopic analysis. The bioactivity of compounds was evaluated by enhanced accumulation of lipids, as measured using Oil Red O staining, and by increased expression of several adipocyte marker genes, including adiponectin in 3T3-L1 adipocytes relative to untreated negative controls. Compared to the plant's 80% EtOH extract, these purified compounds showed significant but still weaker inhibition of TNFα-induced lipolysis in 3T3-L1 adipocytes. This suggests that additional bioactive substances are responsible for the multiple metabolically favorable effects on adipocytes observed with Artemisia scoparia extract.

Sulfone "Geländer" Helices: Revealing Unexpected Parameters Controlling the Enantiomerization Process.

The two sulfonyl-bridged Geländer helices 1a and 2a are obtained by oxidation of the corresponding sulfide bridged precursors 1b and 2b. Both Geländer structures are fully characterized by NMR, high-resolution mass spectrometry, and optical spectroscopies. X-ray diffraction with a single crystal of 2a provides its solid-state structure. Both Geländer helices 1a and 2a are separated into enantiomers, and their racemizations are monitored by circular dichroism. For 1a, consisting of two equally sized macrocycles, a substantial increase in the enantiomerization barrier is observed upon going from the sulfide to the sulfone, and only a subtle rise is detected for the constitutional isomer 2a with two macrocycles of different size during the same transformation. This results not only in 1a with the highest configurational stability in the series of hitherto investigated Geländer structures but also challenges the so far hypothesized correlations between bridging structures and the Gibbs free energy of enantiomerization. The simulation of the enantiomerization process in the macrocyclic subunits suggests the proximity of the endotopic hydrogens as parameter responsible for the heights of the enantiomerization barrier.

Isolation, characterization and semi-synthesis of natural products dimeric amide alkaloids

Isolation, characterization and semi-synthesis of natural products dimeric amide alkaloids

Optical properties, structural, and DFT studies of Pd(II) complexes with 1‐phenyl‐1H‐tetrazol‐5‐thiol, X‐ray crystal structure of [Pd(κ1‐S‐ptt)2(κ2‐dppe)] complex

Seven tetrazole‐thione complexes, [Pd2(κ2‐ptt)4](1), trans‐[Pd(k1‐S‐ptt)2(PPh3)2] (2), trans‐[Pd(k1‐S‐ptt)2(SPPh3)2] (3), trans‐[Pd(k1‐S‐ptt)2(OPPh3)2] (4), [Pd(k1‐N‐ptt)2(k2‐dppe)] (5a), [Pd(k1‐S‐ptt)2(k2‐dppe)] (5b), [Pd(k1‐S‐ptt)2(k2‐dppeS2)] (6), and [Pd(k1‐S‐ptt)2(k2‐dppeO2)] (7), were prepared from 1‐phenyl‐1H‐tetrazole‐5‐thiol (Hptt), with substituted phosphines. These complexes were investigated by CHNS analysis; infrared (IR), nuclear magnetic resonance (NMR) (1H and 31P), and ultraviolet–visible (UV–Vis) spectroscopy; and single‐crystal X‐ray data for 5b. In Complex 1, the ptt− ligand adopted μ2‐ k‐N, k‐S bridging mode to afford a dimeric complex, whereas in Complexes 2–4, 6, and 7, the ptt− was covalently coordinated via sulfur atom of the thiol group as a solo product. In contrast, in Complex 5, the ptt− ligand was bonded in a monodentate fashion through a deprotonated tetrazole ring nitrogen atom in isomer 5a or via a thiolato sulfur atom in isomer 5b. These linkage isomers were clearly shown in the 31P‐{1H} NMR. To explain the adoption of the ligand binding modes in Complexes 5a and 5b, geometry optimization calculations were carried out on two isomers. Very small differences of all molecular parameters were found between 5a and 5b isomers. This confirms the reason for obtaining two isomers. Also, theoretical studies are made for all compounds, and excellent agreement is obtained with experimental data. The direct band gap (Eg) values are equal to 2.88, 2.85, and 2.45 eV for Complexes 1, 2, and 4, respectively, revealing a semiconductor nature. The inhibition activity of Complexes 1–3, 5, and 8 were evaluated versus the growth of four types of bacteria in vitro. The complexes showed a good activity compared with free ligand and a standard antibiotic.

Synthesis, Hirshfeld Surface Analysis and DFT Studies of Ethano-tetracyclic Tetracene Derivatives

The syntheses of ethano-tetracyclic tetracenes; 14-cyano-5,12-dihydro-5,12-ethanotetracen-14-yl acetate (2a and 2b) and 5,12-dihydro-5,12-ethanotetracen-13-one (3) are reported. The tetracenes isomers 2a and 2b are equally obtained via DA reaction and the tetracene 3 is synthesized from the alkaline hydrolysis of 2a and 2b. The DFT calculations of tetracenes isomers 2a and 2b are performed and gave good agreement to the experimental result. The structure of tetracene 3 is elucidated by X-ray technique and its intermolecular interactions are determined by Hirshfeld surface analysis. The crystal system of tetracene 3 is orthorhombic with a Pca21 space group; a = 28.589 (5) A, b = 6.5023 (14) A, c = 7.5101 (11) A, V = 1396.1 (4) A3, Z = 4. This is the first report describing syntheses Ethano-tetracyclic tetracenes 2a, 2b, 3. DFT studies were used to explain the reaction regioselectivity of the two tetracene isomers 2a, 2b. The x-ray is performed to elucidate the structure of tetracene 3. Hirshfeld surface analysis is performed to determine the intermolecular interactions in the crystal structure of the tetracene 3.

Temperature-Dependent Supramolecular Isomeric Zn(II)-Metal–Organic Frameworks and Their Guest Exchange

A pair of three-dimensional metal–organic framework supramolecular isomers (1a and 2a) prepared from the solvothermal reactions of Zn(NO3)2·4H2O, 1,4-bis(4-pyridyl)piperazine (bpp), and 4,4′-oxybis(benzoic acid) (H2obc) in different temperatures was structurally elucidated, and a series of guest exchanges on these isomers were performed without the loss of single crystallinity. At 110 and 130 °C in DMF/H2O, an 8-fold [4 + 4] interpenetrated coordination polymer {[Zn(bpp)(obc)]·3H2O}n (1a) with sra topology and a self-penetrated coordination polymer {[Zn3(bpp)3(obc)3]·2DMF·4H2O}n (2a) with a new topology were isolated, respectively. In the guest-exchange experiments, water molecules in isomer 1a were displaced by acetone and ethylene glycol molecules, while dimethylformamide molecules in isomer 2a were replaced by acetone and ethylene glycol as well as bulkier diethylene glycol due to its larger void. Photoluminescence properties of two isomers and their guest-exchanged products were also measured and discussed.