Three 3D Cu(II) coordination polymers constructed from 1,2,4,5-benzenetetracarboxylate acid and three positional isomeric ligands

Based on 1,2,4,5-benzenetetracarboxylate acid (H₄btc), and mixed with three isomeric dipyridyl ligands, three novel 3D Cu(II) coordination polymers [Cu₂(btc)(4,4′-bpt)]·2H₂O (1) [4,4′-bpt = 1H-3,5-bis(4-pyridyl)-1,2,4-triazole], [Cu(btc)_0.5(3,4′-bpt)]·0.5H₂O (2) [3,4′-bpt = 1H-3-(3-pyridyl)-5-(4-pyridyl)-1,2,4- triazole] and [Cu(btc)_0.5(3,3′-bpt)]·2H₂O (3) [3,3′-bpt = 1H-3,5-bis(3-pyridyl)-1,2,4-triazole] have been synthesized and characterized, respectively. 1 is a 3D pillared double-layer complex containing a novel bilayer unit; 2 is a 3D pillared-layer architecture with (4,4)-sql layer; 3 exhibits a 3D structure containing 3D [Cu(btc)]_∞ motif and 1D [Cu(bpt)]_∞ chain. The topological analysis shows that 1 can be simplified to a (4,6)-connected network with the Schläfli symbol of (4²·6⁴)₂(4⁸·6⁷), 2 a (4,6)-connected network with the symbol of (4⁴·6²)(4⁴·6¹⁰·8), and 3 a four-connected topology with the symbol of (3²·10³·11)₂(3²·10⁴).     

2,2′-Bipyridine-Modified Tamoxifen: A Versatile Vector for Molybdacarboranes

Investigations on the antitumor activity of metallacarboranes are sparse in the literature and limited to a handful of ruthena- and molybdacarboranes. In this study, the molybdacarborane fragment [3-(CO)₂-closo-3,1,2-MoC₂B₉H₁₁] was combined with a vector molecule, inspired by the well-known drug tamoxifen or 4,4′-dihydroxytamoxifen (TAM-diOH). The molybdacarborane derivative [3,3-{4-[1,1-bis(4-hydroxyphenyl)but-1-en-2-yl]-2,2′-bipyridine-κ²N,N′}-3-(CO)₂-closo-3,1,2-MoC₂B₉H₁₁] ( 10 ), as well as the ligand itself 4-[1,1-bis(4-hydroxyphenyl)but-1-en-2-yl]-2,2′-bipyridine ( 6 ) showed cytotoxic activities in the low micromolar range against breast adenocarcinoma (MDA-MB-231, MDA-MB-361 and MCF-7), human glioblastoma (LN-229) and human glioma (U-251) cell lines. In addition, compounds 6 and 10 were found to induce senescence and cytodestructive autophagy, lower ROS/RNS levels, but only the molybdacarborane 10 induced a strong increase of nitric oxide (NO) concentration in the MCF-7 cells.     

Synthesis of [60]Fullerene‐Fused Tetralones via Palladium‐ Catalyzed Ketone‐Directed sp2 C?H Activation and sp3 C?H Functionalization

The palladium‐catalyzed ketone‐directed dual sp² C H activation and sp³ C H functionalization has been applied for fullerene functionalization for the first time. The sec‐alkyl aryl ketones have been exploited to react with [60]fullerene (C₆₀) to provide the novel and scarce C₆₀‐fused tetralones. The combined use of a highly active cationic palladium(II) catalyst and trifluoromethanesulfonic acid is crucial for the improvement of the reaction yield. A plausible reaction mechanism leading to the observed products has been proposed, and the electrochemistry of the fullerene products has also been investigated.

     

Identifizierung von Zwischenprodukten der Lichtinduzierten Spaltung von σ-Alkyl-Co(III)-Komplexen mit Hilfe von spin-trapping-Experimenten

Identification of Intermediates in the Photolysis of Some σ-Alkyl Cobalt Complexes using the Technique of Spin Trapping In the aerobic photolysis of the complexes [R¹Co(chel)Y] (R¹ = CH₃, C₂H₅, n-C₃H₇; chel = salen, salphen; Y = H₂O, C₅H₅N, P(C₆H₅)₃) and [RCo(bipy)₂]X (R² = CH₃, n-C₃H₇, C₆H₅CH₂; X = ClO₄, J) in chloroform alkyl-, alkoxy and hydroxyalkyl radicals are detected using the technique of spin trapping. Moreover, in the presence of phenyl tert.-butyl nitrone the photolysis of the ethyl and propyl complexes [RCo(chel)Y] produces the spin adduct of H at phenyl tert.-butylnitrone. From these results we conclude that photochemically the hydridocomplexes [HCo(chel)Y] are formed.     

Zur Heck-Reaktion von 1-Chloralk-1-inen – Synthese und Charakterisierung von 1,3-disubstituierten 7-(Prop-2-inyliden)bicyclo[2.2.1]heptanen und anderen Bicyclen

The Heck reaction of cyclohexene with 1-chloroalk-1-ynes ClC≡CR 1 (R = Ph a , c-Hex b , n-Bu c , n-Oct d ) using [Pd(OAc)₂]/NaO₂CH/[NEt₃Bz]Cl as catalyst system (DMF, 25 °C) affords 1,3-disubstituted 7-(prop-2-ynylidene)bicyclo[2.2.1]heptanes 2 as tandem products by reaction of cyclohexene and ClC≡CR in a ratio of 1:2. To a smaller extent, substituted 7-[(cyclohexenyl)methylidene]bicyclo-[2.2.1]heptanes 3 (tandem products by reaction of cyclohexene and ClC≡CR in a ratio of 2:1) and the regular Heck products (alkynylcyclohexenes 4 ) are formed. The homocoupling of 1 to give RC≡C–C≡CR does not take place, except for R = n-Oct where it proceeds as side reaction. The analogous reaction of ClC≡CR with cycloheptene affords the 2:1 products (substitued 8-[(cycloheptenyl)methylidene]biyclo[3.2.1]octanes 6 ) as main products and the 1:2 products (1,3-disubstituted 7-(prop-2-ynylidene)bicyclo[3.2.1]-octanes 5 ) as well as the regular Heck products (alkynylcycloheptenes 7 ) as side products. The ratio 5 : 6 is strongly influenced by the ratio cycloheptene : 1 . The products 2 , 5a and 6 were isolated and characterized by means of ¹H and ¹³C NMR spectroscopy. The molecular structures of 7-(1,3-diphenylprop-2-ynylidene)bicyclo[2.2.1]heptane ( 2a ) and 8-[(cyclo-heptenyl)phenylmethylidene)]bicyclo[3.2.1]octane ( 6a ) (as mixture of the cyclohept-3- and -4-enyl double bond isomers) were determined by single-crystal X-ray structure analysis.     

Benzotriazole and benzothiadiazole containing conjugated copolymers for organic solar cell applications

2-Dodecyl benzotriazole (BTz) and benzothiadiazole (BTd) containing copolymers poly(4-(2-dodecyl-2H-benzo[d][1,2,3]triazol-4-yl)benzo[c][1,2,5]thiadiazole (P1), poly(4-(5-(2-dodecyl-7-(thiophen-2yl)-2H-benzo[d][1,2,3]triazol-4-yl)thiophen-2-yl)benzo[c][1,2,5] thiadiazole (P2) and poly(4-(5-(2-dodecyl-7-(4-hexylthiophen-2-yl)-2H-benzo[d] [1,2,3]triazol-4-yl)-3-hexylthiophen-2-yl) benzo[c][1,2,5] thiadiazole (P3) were synthesized via Suzuki polycondensation. We report the application of conjugated copolymers in bulk heterojunction photovoltaic devices. When the copolymers were blended with [6,6]phenyl-C₆₁-butyric acid methyl ester (PCBM), P2 showed the best performance with an open circuit voltage (V_oc), a short-circuit current density (J_sc) and a power conversion efficiency (PCE) of 0.45 V, 3.48 mA cm^?2 and 0.45%, respectively, under AM 1.5G illumination conditions (100 mW cm^?2). The hole mobilities of the devices were calculated from J–V curves using Space Charge Limited Current (SCLC) method and the maximum mobility value was found to be 3.15 × 10^?5 cm² V^?1 s^?1 for the P2:PCBM blend.     

Synthesis,structure and properties of a novel 3D pentanuclear [Zn5(OH)2]8 + cluster-based (3,4,11)-connected coordination polymer

A novel coordination polymer based on the multidentate N-donor ligand 1-((1H-1,2,4-triazol-1-yl)methyl)-3,5-bis(3-pyridyl)-1,2,4-triazole (3,3′-tmbpt) and 1,2,4,5-benzenetetracarboxylate anion (btec), namely, [Zn₅(3,3′-tmbpt)(btec)₂(OH)₂] (1), has been synthesized hydrothermally. Compound 1 displays a rare 3D (3,4,11)-connected framework based on a [Zn₅(OH)₂]^8 + cluster. The optical band gap and photoluminescent property of compound 1 have been studied.     

Evaluation of 5H-Thiazolo[3,2-α]pyrimidin-5-ones as Potential GluN2A PET Tracers

We describe here our efforts to develop a PET tracer for imaging GluN2A-containing NMDA receptors, based on a 5H-thiazolo[3,2-α]pyrimidin-5-one scaffold. The metabolic stability and overall properties could be optimized satisfactorily, although binding affinities remained a limiting factor for in vivo imaging. We nevertheless identified 7-(((2-fluoroethyl)(3-fluorophenyl)amino)-methyl)-3-(2-(hydroxymethyl)cyclopropyl)-2-methyl-5H-thiazolo-[3,2-α]pyrimidin-5-one ([¹⁸F] 7b ) as a radioligand providing good-quality images in autoradiographic studies, as well as a tritiated derivative, 2-(7-(((2-fluoroethyl)(4-fluorophenyl)amino)methyl)-2-methyl-5-oxo-5H-thiazolo[3,2-α]pyrimidin-3-yl)cyclopropane-1-carbonitrile ([³H₂] 15b ), which was used for the successful development of a radioligand binding assay. These are valuable new tools for the study of GluN2A-containing NMDA receptors, and for the optimization of allosteric modulators binding to the pharmacophore located at the dimer interface of the GluN1-GluN2A ligand-binding domain.     

Characterization of block copolymers based on poly[3,3-bis(ethoxymethyl)oxetane] and other novel polyethers

Diblock, triblock, and alternating block copolymers based on poly[3,3-bis(ethoxymethyl) oxetane] [poly(BEMO)] and a random copolymer center block poly(BMMO-co-THF) composed of poly[3,3-bis(methoxymethyl)oxetane] [poly(BMMO)], and poly(tetrahydrofuran) [poly(THF)] were synthesized and characterized with respect to molecular weight. Glass transition temperatures T_g and melting temperatures T_m were characterized via DSC, modulus–temperature, and dynamic mechanical spectroscopy (DMS). These polyethers had T_m between 70°C and 90°C, and T_g between ?55°C and ?30°C. The degree of crystallinity of poly(BEMO) was found to be 65% by X-ray powder diffraction. Tensile properties of the triblock copolymer, poly(BEMO-block-BMMO-co-THF-block-BEMO) were also studied. A yield point was found at 4.1 × 10⁷ dyn/cm² and 10% elongation and failure at 3.8 × 10⁷ dyn/cm² and 760 % elongation. Morphological features were examined by reflected light microscopy and the kinetics of crystallization were studied. Poly(BEMO) and its block copolymers were found to form spherulites of 2–10 μm in diameter. Crystallization was complete after 2–5 min.     

Quinoxaline derivatives as long wavelength photosensitizers in photoinitiated cationic polymerization of diaryliodonium salts

The present paper is focused on visible light initiated cationic polymerizations. Photoinitiated polymerization of representative vinyl ether and oxirane monomers using two quinoxaline derivatives; namely (2-(2,3-dihydrobenzo [b][1,4]dioxin-6-yl)-3-(2,3-dihydrobenzo[b]-[1,4]dioxin-7-yl)-5-(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-8-(2,3-dihydrothieno[3,4-b][1,4]dioxin-7yl) quinoxaline) (DBQEd) and 2,3,5,8-tetra(thiophen-2-yl)quinoxaline (TTQ) are studied. Novel dyes based on the quinoxaline skeleton are employed as efficient photosensitizers in cationic photopolymerizations. Polymerizations were initiated at room temperature upon irradiation with long-wavelength UV and visible lights in the presence of diphenyliodonium hexafluorophosphate (Ph₂I⁺PF₆^?). The progress of the polymerizations was monitored by optical pyrometry (OP). Solar irradiation is also employed to carry out the cationic polymerization of a diepoxide monomer in the presence of air.     

Pyryliumverbindungen. XXVII. Spezifisch deuterierte Carbo- und Heterocyclen via 2,4,6-Triaryl-[3,5-2H2]pyryliumsalze

Pyrylium Compounds. XXVIII. Specifically Deuterated Carbo- and heterocycles via 2,4,6-Triaryl[3,5-²H₂]pyrylium Salts On heating with catalytic amounts of bases(e.g. triethyl amine) in deuterated alcohols such as methan[²H]ol or ethan[²H]ol pseudobases of 2, 4, 6-triarylpyrylium salts 1 undergo fast¹H/²H isotopic exchange reaction affording 1, 3, 5-triaryl[2, 4, 4-²H₃]pent-2-ene-1,5-diones which with [²H] perchloric acid give highly deuterated 2, 4, 6-triaryl-[3, 5-²H] pyrylium perchlorates 8 . These salts are obtainable also directly from 1 through a one-pot procedure by ring opening of the latter with deuterium oxide under the above-mentioned¹H/²H isotopic exchange conditions followed by recyclization of the formed 1, 3, 5-triaryl[2, 4, 4-²H₃]pent-2-ene-1, 5-diones with [²H]ClO₄. Ring transformations of 2, 4, 6-triphenyl[3, 5-²H²]pyrylium perchlorate (8a) to 2, 4, 6-triphenyl[3, 5-²H₂]nitrobenzene (9) 2, 4, 6-triphenyl[3, 5-²H₂]pyridine (10) , 1, 2, 4, 6-tetraphenyl[3, 5-²H₂]pyrydinium perchlorate (11) , 2, 4, 6-triphencyl[3, 5-²H₂]thiopyrylium perchlorate (12) , 2-benzoyl-3, 5-diphenyl[4-²H]furan (13) , and 3, 5, 7-triphenyl-[4, 4, 6-²H₃]4H-1, 2-diazepin (14) demonstrate the usability of pyrylium salts of type 8 as starting materials for syntheses of specifically deuterated carbo- and hetrocycles.     

Unique entangled Cu(II)-MOF featuring self-penetrating and polyhelix motifs generated from rigid azobenzenetetracarboxylic acid and N-donor coligands

A unique 3D entangling Cu(II)-metal organic framework, namely, {[Cu₄(abtc)₂(btab)₆·3H₂O]·2H₂O}_n (1), has been successfully constructed from Cu^II and 3,3′,5,5′-azo benzene tetracarboxylate building units with the aid of N-donor bridging spacers [1,4-bis(triazol)butane], and directs a rare self-penetrating structure with polyhelix motifs and presents a new (4,4,8)-connected (4.6⁵)₂(6⁴.7.8)₂(4².6²⁰.7².8⁴) topology. The magnetic investigations demonstrate that complex 1 exhibits antiferromagnetic coupling interaction between the adjacent Cu(II) ions.     

Electropolymerization and characterization of terpyridinyl iron (II) and ruthenium (II) complexes

Electroactive 2,2′: 6,2″-terpyridinyl ligands ( 3, 5, 6 ) and their iron(II) ( 7a–9a ) and ruthenium(II) complexes ( 7b–9b ) were synthesized. Bis[3-(aminophenyl)-2,2′ :6,2″-terpyridinyl]metal(II) complexes ( 7a, 7b ) and bis[2-(hydroxyphenyl)-2,2′ :6,2″-terpyridinyl]metal(II) complexes ( 8a, 8b ) were electropolymerized on to the surface of Pt or In-SnO₂ (ITO) electrodes in acetonitrile containing Bu₄NCIO₄ by scanning the potential between O and + 1.6V (for 7a and 7b ), and ?0.8 and +1.6V (for 8a and 8b ) versus saturated calomel electrode. The electrodes obtained by electropolymerization exhibited reversible electrochromism based on Fe(II)/Fe(III) or Ru(II)/Ru(III) redox couple. Photoresponses to visible light were found in the modified electrode obtained by electropolymerization of ruthenium complex 7b in an aqueous LiClO₄ solution containing methylviologen (cation MV²⁺) under an O₂ atmosphere. The mechanism for the photoresponded cathodic current was explained in terms of an excitation of bis(terpyridinyl)ruthenium(II) complex [Ru(terpy)²₂⁺] by visible light, an electron transfer from the excited state [Ru(terpy)^2+*₂] to MV²⁺, reduction of Ru(terpy)³⁺₂ at an electrode, and oxidation of MV^+* with O₂.     

Dissecting Anion Effects in Gold(I)‐Catalyzed Intermolecular Cycloadditions

From a series of gold complexes of the type [t‐BuXPhosAu(MeCN)]X (X=anion), the best results in intermolecular gold(I)‐catalyzed reactions are obtained with the complex with the bulky and soft anion BAr₄^F− [BAr₄^F−=3,5‐bis(trifluoromethyl)phenylborate] improving the original protocols by 10–30% yield. A kinetic study on the [2+2] cycloaddition reaction of alkynes with alkenes is consistent with an scenario in which the rate‐determining step is the ligand exchange to generate the (η²‐phenylacetylene)gold(I) complex. We have studied in detail the subtle differences that can be attributed to the anion in this formation, which result in a substantial decrease in the formation of unproductive σ,π‐(alkyne)digold(I) complexes by destabilizing the conjugated acid formed.

     

Pericyclic Organometallic Reactions. Substituent Effects on Cycloadditions and Rearrangements of (η4-cycloheptatriene)Fe(CO)3 Derivatives

The mechanism of the reactions of (η⁴-cycloheptatrien-1-al)Fe(CO)₃ and its ethyleneglycol acetal with tetracyanoethylene (TCNE) was studied. The aldehyde undergoes a fast reversible 3+2 cycloaddition involving the free aldehyde-substituted double bond, and a slow irreversible 3+2 cycloaddition at the coordinated site. The latter, σ,π-allylic complex undergoes a slow interconversion with the corresponding 5 +2 isomer via the pericyclic [3,3]-sigmahaptotropic rearrangement. In contrast, the acetal reacts with TCNE at the free acetal-substituted double bond to give a single kinetic 3+2 adduct, which, under thermodynamic conditions, undergoes a [4,4]-sigmahaptotropic rearrangement to the 6 + 2 adduct. The reaction kinetics was followed by ¹H NMR. The effect of substituents on the reaction course is discussed, and the detailed mechanism of both the cycloadditions and rearrangements is described.     

Über neue Pyrazolverbindungen. IV Darstellung und Cyclisierungsverhalten einiger akzeptorsubstituierter N-(Pyrazol-3-yl)-thioharnstoffe

New Pyrazol Derivatives. IV. Preparation and Cyclization of Some Acceptor-Substituted N-(Pyrazol-3-yl)-thioureas . 3-Aminopyrazol-4-carboxylic acid derivatives ( 1 , 2 ) were transformed by reaction with different isothiocyanates R²NCS to N-(pyrazol-3-yl)-N^. -substituted thioureas ( 5 , 6 ). Ethyl 3-amino-1-benzylpyrazol-4-carboxylate reacts with CSCl₂ to form ethyl 1-benzyl-3-isothiocyanatopyrazol-4-carboxylate ( 3 ) which yields with amines the corresponding N-(pyrazol-3-yl)-N^. -substituted thioureas ( 5 ). As a byproduct in the reaction with CSCl₂ N,N^. -di-(pyrazol-3-yl)-thiourea ( 4 ) is formed. With hydrazine or phenylhydrazine N-(pyrazol-3-yl)-thiosemicarbazides ( 7a , b ) are obtained. The thioureas ( 5 , 6 ) can be cyclized in basic solution to 4,5,6,7-tetrahydropyrazolo[3,4-d]pyrimidin-4-on-6-thiones ( 8 ) which on alkylation form 6-alkylthio-4,5-dihydropyrazolo[3,4-d]pyrimidin-4-ones ( 9 ). Methyl-N-(pyrazol-3-yl)-N^.-benzoylisothiourea ( 10 ) reacts with ethylamine to form N-benzoyl-N^. -ethyl-N^‥-(pyrazol-3-yl)-guanidine derivative ( 11 ) which on treatment with NaH in dimethylformamide yields 6-benzoylamino-5-ethyl-4,5-dihydropyrazolo[3,4-d]pyrimidin-4-one ( 12 ). By treatment with sulfuric acid the N-(pyrazol-3-yl)-thiourea derivatives ( 5 , 6 ) form new 6-amino substituted pyrazolo[3,4-d][1,3]thiazin-4-ones ( 13 ).     

The synthesis and complexation study of some novel 3-methoxyphenyl chromenone crown ethers using conductometry

7,8-Dihydroxy-3-(3,4-dimethoxyphenyl)-2H-chromenones, 7,8-dihydroxy-3-(3,5-dimethoxyphenyl)-2H-chromenones and 7,8-dihydroxy-3-(3,4,5-trimethoxyphenyl)-2H-chromenones, o-dihydroxy-3-methoxyphenylcoumarins, were prepared from 2,3,4-trihydroxybenzaldehyde and corresponding methoxyphenylacetic acid in NaOAc/Ac₂O, respectively. 3-Methoxyphenyl-7,8-dihydroxy-2H-chromenone reacted with the polyethylene glycol ditosylate or dichloride in CH₃CN/alkali carbonate to afford [12]crown-4, [15]crown-5 and [18]crown-6-chromonones.The chromatographically purified novel chromenone crown ethers were identified with IR, ¹H NMR, ¹³C NMR and low and high resolution mass spectroscopy and elemental analysis.Stability constants for the 1:1 complexes of Na⁺ and K⁺ with different substituted methoxyphenyl derivatives of coumarino[12]crown-4, coumarino[15]crown-5 and coumarino[18]crown-6 (5a–5i) have been determined by conductometry at 25 °C in a binary solvent, dioxane/water. For all the coumarino crown ether derivatives, the stability constant decreases for K⁺ ion compared to Na⁺ ion.The selectivity sequence of these crown ethers in dioxane/water has showed an irregular order with respect to their cavity size.     

Copper‐Catalyzed Oxidative Transformation of Secondary Alcohols to 1,5‐Disubstituted Tetrazoles

A mild and convenient oxidative transformation of secondary alcohols to 1,5‐disubstituted tetrazoles is uncovered by employing trimethylsilyl azide (TMSN₃) as a nitrogen source in the presence of a catalytic amount of copper(II) perchlorate hexahydrate [Cu(ClO₄)₂^.6 H₂O] (5 mol%) and 2,3‐dichloro‐5,6‐dicyano‐para‐benzoquinone (DDQ) (1.2 equiv.) as an oxidant. This reaction is performed under ambient conditions and proceeds through C C bond cleavage.

     

Syntheses of radioactive furan fatty acids

A novel route for the synthesis of naturally occurring furan fatty acids with particular emphasis on labeling with¹⁴C is described. Methyl [2-¹⁴C] 9-(5-pentyl-3,4-dimethyl-2-furyl)nonanoate was synthesized from 3,4-dimethyl-2-pentylfuran by a new route. [3-¹⁴C]11-(5-Pentyl-3-methyl-2-furyl)undecanoate and [2-¹⁴C] 9-(5-pentyl-2-furyl)nonanoate were prepared from their lower homologs. The label was introduced in all cases by means of the Arndt-Eistert method for chain elongation, using¹⁴CH₂N₂. Comparisons of yields show that, with increasing number of substituents on the ring, the furan compounds are increasingly subject to uncontrollable side reactions.