Variable behaviour of a flexible bispyrazole ligand: A Co(II) polymer and a unique Cu(II) penta-coordinated dimer

Hoping to highlight the flexibility of a bispyrazole ligand possessing an ether chain including a weak spot (1,2-bis([4-(3,5- dimethyl -1 H - pyrazol -1- yl )-2- oxabutyl ]benzene ( L )), its reactivity against coordinatively flexible metal centres has been assayed. Thus Co(II) and Cu(II) coordination complexes of L have been synthesized and fully characterized by analytical and spectroscopical methods. Their X-ray crystal struc- ture elucidation has allowed to ascertain that while the Co(II) compound {[C o ( L )C l 2 ] ·1/2H 2 O} n ( 1 ) pos- sesses a polymeric structure, much like its Zn(II), Cd(II) and Hg(II) analogues, the Cu(II) compound [Cu 2 L Cl 4 ] ( 2 ) displays a completely unexpected dimeric architecture. The previously unreported coordi- nation mode of the ligand in the Cu(II) compound causes dramatical changes in the morphology of the resulting complexes. Their crystal structures are discussed in deep, and the causes behind their differing architectures are examined through comparison with bibliographical referencesLa Caixa Foundation CB615921 CB616406Generalitat de Catalunya 2017/SGR/1687Universitat Autonoma de Barcelon

Variable behaviour of a flexible bispyrazole ligand: A Co(II) polymer and a unique Cu(II) penta-coordinated dimer

Hoping to highlight the flexibility of a bispyrazole ligand possessing an ether chain including a weak spot (1,2-bis([4-(3,5- dimethyl-1H- pyrazol-1- yl) -2-oxabutyl]benzene (L)), its reactivity against coordinatively flexible metal centres has been assayed. Thus Co(II) and Cu(II) coordination complexes of L have been synthesized and fully characterized by analytical and spectroscopical methods. Their X-ray crystal struc-ture elucidation has allowed to ascertain that while the Co(II) compound {[Co(L)Cl-2]center dot 1/2H(2)O}(n) (1) possesses a polymeric structure, much like its Zn(II), Cd(II) and Hg(II) analogues, the Cu(II) compound [Cu2LCl4] (2) displays a completely unexpected dimeric architecture. The previously unreported coordi-nation mode of the ligand in the Cu(II) compound causes dramatical changes in the morphology of the resulting complexes. Their crystal structures are discussed in deep, and the causes behind their differing architectures are examined through comparison with bibliographical reference

Solvent-controlled formation of monomeric and dimeric species containing Cu(II) acetate and 4-phenylpyridine

Three copper(II) acetate complexes with 4-phenylpyridine (4-Phpy), namely [Cu(MeCO2)2(4- Phpy)2(H2O)2] (1), [Cu(MeCO2)2(4-Phpy)2(H2O)1.5] (2) and [Cu(MeCO2)2(4-Phpy)]2 (3), were synthesized and characterized by analytical and spectroscopic methods. Experimental conditions as solvent or temperature determine the species obtained. Crystal and molecular structure of 2 was determined by Xray diffraction. Compound 2 presents a singular structure, containing two crystallographic independent mononuclear units [Cu(MeCO2)2(4-Phpy)2(H2O)2] (2A) and [Cu(MeCO2)2(4-Phpy)2(H2O)] (2B) in its unit cell and each of these forms an independent 1-D chain through H-bonding

Copper complexes from 3,5-disubstituted N-hydroxyethylpyrazole ligands: Cleavage of C-N bond as well as formation of second coordination sphere complexes

The coordination behaviour of two N,O-hybrid hydroxyethylpyrazole ligands, 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethanol, HL1; and (2-(3,5-di(2-pyridyl)-1H-pyrazol-1-yl)ethanol, HL2; with CuCl2·2H2O and Cu(NO3)2·3H2O were studied. Four copper complexes: [CuCl(µ-L1)]2·HL1 (1), [CuCl2(HL2)]·H2O (2A), [Cu(NO3)(3,5-hdppz)(µ-L1)]2·2CH3CN (3), (3,5-hdppz = 3,5-diphenylpyrazole) and [Cu(H2O)(3,5-dpypz)]2(NO3)2·H2O (4), (3,5-dpypz = 3,5-(2-pyridyl)pyrazolate) were isolated and characterized by analytical methods and spectroscopical studies. From their crystal structure, a Npz-C bond cleavage was observed for HL1 and HL2 upon reaction with Cu(NO3)2·3H2O, yielding the unexpected complexes 3 and 4, respectively. Overall, these complexes provided great structural diversity, as dimers (asymmetric and symmetric), monomers and ionic complexes were obtained. Finally, magnetic susceptibility measurements for 3 were carried out, showing the dependence of the magnetic moment on Cu-O-Cu angles

Mononuclear and binuclear copper(II) bis(1,3-benzodioxole-5-carboxylate) adducts with bulky pyridines

Copper(II) bis(1,3-benzodioxole-5-carboxylate) adducts with bulky pyridines have been prepared from the reaction of copper(II) acetate with 1,3-benzodioxole-5-carboxylic acid (piperonylic acid, HPip) and an excess of pyridine derivatives (3-phenylpyridine, 3-Phpy, 4-phenylpyridine, 4-Phpy, or 4-benzylpyridine, 4-Bzpy). Using 3-Phpy or 4-Bzpy binuclear paddle wheel compounds ([Cu(μ-Pip)2(3-Phpy)]2 (1) and [Cu(μ-Pip)2(4-Bzpy)]2 (3), and mononuclear complexes [Cu(μ-Pip)2(3-Phpy)2(H2O)] (2) and {[Cu(Pip)2(4-Bzpy)2]}{[Cu(Pip)2(4-Bzpy)2](HPip)}·{4A}{4B} have been isolated. Mononuclear 2 can also be produced from 1 in presence of an excess of 3-Phpy, while low thermal treatment of 2 at 70 °C, in absence of solvent, reverts to the formation of 1. On the other hand, 4 presents a singular structure that contains two independent mononuclear units {4A} and {4B}. Working with 4-Phpy yields crystalline binuclear [Cu(μ-Pip)(Pip)(4-Phpy)2]2·4CH3OH (5). In this complex only half of the carboxylate ligands bridge copper atoms, being one of the rare examples of this flat core. Its crystal structure contains a significant fraction of volume filled with methanol that is partly lost simply by exposing the solid to air. However, this process is related to an irreversible structure collapse, showing that the intermolecular interactions after methanol removal are not enough to support a porous structure

Synthesis, crystal structure and magnetic properties of a Cu(II) paddle-wheel complex with mixed bridges

The synthesis and characterization of a mixed carboxylate paddle-wheel copper complex, with formula [Cu(μ- Pip)(μ-MeCO2)(MeOH)]2 (Pip = piperonylate or 1,3-benzodioxole-5-carboxylate and MeCO2 = acetate), is here reported. The described compound is a binuclear complex, each pair of similar carboxylate ligands occupyingmutually trans bridging positions,while the methanol occupies the apical positions. The dimers are arranged into 2D layers in the bc plane through a network of O-H⋯O hydrogen bonds established between themethanol and the acetate ligand. Magnetic studies showed a strong antiferromagnetic Cu⋯Cu interaction (J = −308 cm−1), in agreement with the presence of four μ-κO-κO′ carboxylates bridging the metallic centers in the binuclear complex

Modulating p-hydroxycinnamate behavior as a ditopic linker or photoacid in copperth) complexes with an auxiliary pyridine ligand

The reaction of copper(II) acetate monohydrate with p-hydroxycinnamic acid (HpOHcinn) and different pyridine derivatives (4-tert-butylpyridine, 4-tBupy; 4-acetylpyridine, 4-Acpy; 3-phenylpyridine, 3-Phpy; 4-phenylpyridine, 4-Phpy) was essayed in methanol solvent at room temperature. The crystal structures of the resulting compounds were elucidated. Their analysis shows that the choice of pyridine ligands determines different coordination modes of the pOHcinn ligand and the Cu(II) coordination, nuclearity and geometry. The pOHcinn acts as a monodentate carboxylate ligand in combination with 4-tBupy or 4-Phpy, yielding monomers and dimers, associated by hydrogen bonds into supramolecular networks in which the phenol group plays a key role. Conversely, in combination with 4-Acpy or 3-Phpy, the phenol group coordinates directly to the Cu(II), acting as a ditopic ligand and yielding 2D coordination polymers. The compound containing 3-Phpy shows interesting MeOH-H2O reversible exchange behavior. Not only has the pyridine auxiliary ligand had a tremendous effect on the coordination mode of pOHcinn, but also its reactivity is influenced. Particularly, in the case of the compound containing 4-Phpy, it undergoes a photoinduced process, in which the phenol group deprotonates and coordinates to Cu(II) as a phenoxy ligand. This yields a coordination polymer in which two different dimers alternate, bridged by the resulting pOcinn ligand. The magneto-structural correlation of this compound is also discussed

Synthesis and characterization of three new Cu(II) paddle-wheel compounds with 1,3-benzodioxole-5-carboxylic acid

Three different paddle wheel compounds have been synthesized, each one via a different synthetic pathway. The first method is the reaction of Cu(MeCO2)2 H2O with 1,3-benzodioxole-5-carboxylic acid (Piperonylic acid, HPip) in a MeOH solution, yielding [Cu(m-Pip)2(MeOH)]2 (1). The second method is the transformation of the heteroleptic core paddle-wheel compound [Cu(m-MeCO2)(m-Pip)(MeOH)]2 into the homoleptic core paddle-wheel [Cu(m-Pip)2(DMSO)]2 2DMSO (2). Lastly, the third method is the substitution of the solvent molecule (DMF) present in the molecular array [Cu(m-Pip)2(DMF)]2 by 2-benzylpyridine (2-Bzpy) ligand, resulting in [Cu(m-Pip)2(2-Bzpy)]2 2.5MeOH H2O (3a). All compounds are characterized via EA, PXRD, ATR-FTIR, Far-IR and UV-Vis spectroscopy. For all three compounds, the X-ray crystal structure has been determined and their extended structures are discussed. Finally, TG/DTA measurements have been recorded

Tuning the architectures and luminescence properties of Cu(I) compounds of phenyl and carboranyl pyrazoles: the impact of 2D versus 3D aromatic moieties in the ligand backbone

This work was financially supported by MICINN (PID2019-106832RB-I00, PGC2018-093863-B-C21), MICINN through the Severo Ochoa Program for Centers of Excellence for the FUNFUTURE (CEX2019-000917-S and MDM-2017-0767 projects) and the Generalitat de Catalunya (2017/SGR/1720 and SGR2017-1289). D. Ch.-L. acknowledges funding by project no. PGC2018-102047-B-I00 (MCIU/AEI/FEDER, UE). J. Soldevila-Sanmartin is enrolled in the UAB PhD program and acknowledges the PIF pre-doctoral Fellowship from the UAB for his pre-doctoral grant (no. 19032/2). E. R. acknowledges computer resources, technical expertise and assistance provided by the CSUC. We thank Prof. D. Ruiz and Dr C. Roscini for the quantum yield measurements. The present publication is dedicated to Prof. Elena Shubina on the occasion of her 70th birthday.Incorporation of one or two o-carborane moieties at the backbone of the pyrazole ring was achieved by lithiation and nucleophilic addition onto the corresponding 3,5-dimethyl-1-(2-toluene-p-sulfonyloxyethyl)pyrazole. Two monosubstituted carboranyl pyrazoles (L2 and L3) and one disubstituted carboranyl pyrazole (L4) were synthesized and fully characterized. All new compounds, and the corresponding monosubstituted phenylderivative (L1) behave as N-type ligands upon coordination with CuI to afford different polynuclear Cu(I) compounds 1-4. Compounds 1-4 were fully characterized and their molecular structures were determined by X-ray diffraction. It is noteworthy that whereas the pyrazolylphenyl ligand L1, without o-carborane, provides a 1D coordination polymer (1), ligands containing carborane, L2-L3, affords 0D coordination compounds 2 and 3, and disubstituted carboranyl pyrazole ligand L4 gives rise to a 3D coordination polymer. The photoluminescence behaviour of compounds 1-4 has been investigated in the solid state and by TDDFT calculations for molecular compounds 2 and 3. Complex 2 exhibits blue emission with a maximum at 483 nm and a high fluorescence quantum yield of 66.5%. According to TDDFT calculations the emission occurs from LUMO to HOMO-1 and HOMO-2 and deexcitation could be described as cluster-centred excited state of d-s transition in origin. This result contradicts previous studies of scarce tri-coordinated rhombohedral Cu(I) clusters, where it was assumed the origin of their emissions is (X + M)LCT in nature by analogy with tetra-coordinated rhombohedral Cu(I) clusters. Complex 3 exhibits very weak emission (Phi(F) of 5%) in the green region with a maximum at 517 nm, which according to TDDFT is through a (CC)-C-3 state. Calculations also show that, upon excitation, 3 suffers a notable distortion resulting in the total cleavage of the Cu4I4 framework. This cleavage could be the cause of the relatively large Stokes shift observed for 3. To the best of our knowledge, this is the first time that such behaviour is observed for this type of octahedral compounds. Additionally, the 1D polymer 1 exhibits weak fluorescence emission in the orange range with a maximum at 609 nm and a remarkable Stokes shift, whereas the 3D polymer 4 exhibits a similar emission to compound 2, with a moderate quantum yield (FF of 13.7%).Spanish Government European Commission PID2019-106832RB-I00 PGC2018-093863-B-C21MICINN through the Severo Ochoa Program for Centers of Excellence for the FUNFUTURE CEX2019-000917-S MDM-2017-0767Generalitat de Catalunya 2017/SGR/1720 SGR2017-1289MCIU/AEI/FEDER, UE PGC2018-102047-B-I00UAB 19032/

Pyrazole as a framework for ligand design: synthesis of new ligands and coordination compounds

Aquesta tesi doctoral tracta principalment de la síntesi i caracterització de lligands derivats del pirazol i dels compostos de coordinació obtinguts a partir d’aquests. Els lligands emprats en aquest treball són pirazols trisubstituïts (posicions 1- (N-substitució), 3- i 5-), que es poden classificar en tres grups: N-hidroxietilpirazols, bispirazol èter i N-alquilcarborà pirazols. Durant aquest treball s’han sintetitzat sis lligands nous, i s’han obtingut trenta-dos complexos de coordinació. Al Capítol 1 s’hi ofereix una visió global del treball dut a terme dins el grup “Design of Metal Organic Materials” (DMOM) en la síntesi de lligands derivats del pirazol, així com del treball dut a terme dins el grup “Laboratory of Inorganic Materials and Catalysts” (LMI) en la incorporació de grups N-heterocíclic a carborans. Al Capítol 2 s’hi detallen els objectius generals i específics d’aquesta tesi. Els resultats obtinguts es poden trobar en el Capítol 3, que es troba dividit en cinc seccions: La secció 3.1 conté la síntesi i caracterització de sis nous lligands derivats del pirazol. Els primers (L6-L8), pertanyen al grup dels bispirazol èters, i incorporen grups fenils a les posicions 3- i 5-. Els darrers (L9-L11), són els primers exemples de lligands N-alquilcarborà pirazol. A la secció 3.2 s’hi descriu la reactivitat de tres lligands N-hidroxietilpirazol incorporant grups metil, fenil o 2-piridil (HL1-HL3) amb diferents sals de Cu(II). S’han resolt les estructures cristallines dels nou compostos obtinguts, permeten l’estudi de les seves estructures moleculars i xarxes supramoleculars. Aquests estudis demostren que el grup alcohol es el principal condicionant de la morfologia dels compostos resultants. La secció 3.3 està dedicada als lligands bispirazol èter. A la primera part s’hi estudia la reactivitat de dos isòmers posicionals de un lligand bispirazol (L4 i L5) amb diferents sals del tipus MCl2 (M = Zn(II), Cd(II), Hg(II), Co(II) i Cu(II)). S’han aïllat deu compostos de coordinació amb tres motius estructurals diferents: metal·lacicles dimèrics amb L4 i polímers 1D i dímers per a L5, demostrant que la posició relativa dels substituents en aquests lligands té un efecte directe en la morfologia dels compostos resultants. A la segona part, la s’hi examina la reactivitat dels nous lligands L6-L8 amb Pd(II), i es comparen els resultats amb aquells obtinguts prèviament amb L4 i L5. Els compostos de coordinació dels lligands del tipus N-alquilcarborà pirazol són descrits per primer cop a la secció 3.4. S’han obtingut sis compostos de coordinació amb els lligands L9-L11 amb els metalls Cu(II), Zn(II), Cd(II), Hg(II) i Pd(II), permeten l’observació de l’efecte de la incorporació del grup carborà a l’anell pirazòlic. A la secció 3.5 es descriu la obtenció de quatre compostos luminescents de Cu(I), incorporant els lligands L9-L12. Alguns d’ells mostres motius estructurals rars, i la obtenció d’aquests en el mateix treball és un fet destacable. A més, la investigació de les seves propietats fotofísiques ha permès estudiar els processos d’emissió de compostos amb morfologies escassament estudiades. Aquests estudis s’han completat amb càlculs TDDFT. Les conclusions generals d’aquest treball es presenten al Capítol 4. Finalment, aquest treball conta amb una secció experimental (Capítol 5) i un annex (Annex I) on s’hi poden trobar tots els espectres i d’altra informació addicional. Les publicacions relacionades amb aquesta tesi es llisten al Annex II.Esta tesis doctoral versa sobre la síntesis y caracterización de ligandos derivados del pirazol, y de los compuestos obtenidos a partir de dichos ligandos. Los ligandos utilizados son pirazoles trisustituidos (posiciones 1- (N-sustitución), 3- y 5-), que se pueden clasificar en tres grupos: N-hidorxietilpirazoles, bispirazol éter y N-alquilocarborano pirazol. Durante este trabajo se han sintetizado seis nuevos ligandos y se han obtenido treinta y dos compuestos de coordinación. En el Capítulo 1 se ofrece una visión global del trabajo llevado a cabo en el grupo “Design of Metal Organic Materials” (DMOM) en la síntesi de ligandos derivados del pirazol, así como del trabajo llevado a cabo por el grupo “Laboratory of Inorganic Materials and Catalysts” (LMI) en la incorporación de grupos N-heterocíclicos a los carboranos. En el Capítulo 2 se detallan los objetivos generales y específicos de esta tesis. Los resultados obtenidos se describen en el Capítulo 3, dividido en cinco secciones: La sección 3.1 contiene la síntesis y caracterización de seis nuevos ligandos derivados del pirazol. Los primeros tres (L6-L8), pertenecen al grupo de los bispirazol éter, y poseen grupos fenilo en las posiciones 3- y 5-. Los últimos tres (L9-L11), son los primeros ejemplos de ligandos N-alquilocarborano pirazol. En la sección 3.2 se describe la reactividad de tres ligandos N-hidroxietilpirazol incorporando grupos metilo, fenilo y 2-piridil (HL1-HL3) con diferentes sales de Cu(II). Se han resuelto las estructuras cristalinas de los nueve compuestos obtenidos, permitiendo el estudio de su estructura molecular y sus redes supramoleculares. Estos estudios demuestran que el rol del grupo alcohol es determinante en la morfología de los compuestos resultantes. La sección 3.3 se centra en los ligandos bispirazol éter. En la primera parte se describe la reactividad de dos isómeros posicionales de un ligando bispirazol (L4 i L5) con distintas sales MCl2 (M = Zn(II), Cd(II), Hg(II), Co(II) i Cu(II)). Se han aislado diez compuestos de coordinación con tres motivos estructurales distintos: metalaciclos diméricos con L4 y polímeros y dímeros con L5, demostrando que la posición relativa de los sustituyentes en estos ligandos tiene un claro efecto en la topología de los compuestos resultantes. En la segunda parte, se examina la reactividad de los nuevos ligandos L6-L8 con Pd(II), comparándose los resultados con los obtenidos previamente para L4 y L5. Los compuestos de coordinación con ligandos N-alquilocarborano pirazol se describen por primera vez en la sección 3.4. Se han obtenido seis compuestos con los ligandos L9-L11 y los metales Cu(II), Zn(II), Cd(II), Hg(II) y Pd(II), que permiten observar el efecto de la incorporación de el grupo carborane al anillo pirazólico. En la sección 3.5 se describe la obtención de cuatro compuestos luminiscentes de Cu(I) con los ligandos L9-L12. Algunos de ellos poseen motivos estructurales poco usuales, y su obtención en un mismo trabajo es un hecho destacable. La investigación de sus propiedades fotofísicas ha permitido estudiar los procesos emisivos de compuestos con morfologías escasamente estudiadas. Este trabajo se ha completado con cálculos TDDFT. Las conclusiones generales se presentan en el Capítulo 4. Finalmente, este trabajo cuenta con una sección experimental (Capítulo 5) y un anexo (Anexo I) dónde se pueden encontrar todos los espectros y otra información adicional.This PhD mainly revolves about the synthesis of pyrazole-derived ligands and their coordination compounds. The particular ligands used in this work are tri-substituted pyrazole rings (positions 1- (N-substitution), 3- and 5-), which can be classified in three families: N-hydroxyethylpyrazole, bispyrazole ether and N-alkylcarborane ligands. In this work, six previously unreported ligands have been synthesized for the first time, and thirty-two metal complexes have been obtained. Chapter 1 starts by offering an overview of the Design of Metal Organic Materials (DMOM) group past work in the synthesis of pyrazole-derived ligands as well as in the background of the Laboratory of Inorganic Materials and Catalyst’s (LMI) group in incorporating N-heterocycles to the carborane moiety. Chapter 2 states the general and specific objectives for this thesis. Chapter 3, where the results obtained during this work are discussed, is divided in five sections: Section 3.1 contains the synthesis and characterization of six new pyrazole derived ligands. The first three (L6-L8) belong to the bispyrazole ether family, and incorporate phenyl moieties in positions 3- and 5-. The next three (L9-L11) are the first examples of N-alkylcarborane pyrazole ligands. Section 3.2 describes the reactivity of a family of three different N-hydroxyethylpyrazole ligands bearing methyl, phenyl or 2-pyrydil groups (HL1-HL3) against different Cu(II) salts. The crystal structures of the nine resulting compounds have been elucidated, allowing the study of their molecular structures and supramolecular networks. These studies lead to the assessment that the alcohol moiety is the key player in determining the nuclearity of the resulting compounds. Section 3.3 focuses on bispyrazole ether ligands. In the first part, the reactivity of two positional isomers of a bispyrazole ligand (L4 and L5) against different MCl2 salts (M = Zn(II), Cd(II), Hg(II), Co(II) and Cu(II)) has been assayed. This afforded ten coordination compounds bearing three clearly different topological motifs: dimeric metallacycles for L4, and 1D polymers and dimers for L5, demonstrating the effect of the relative position of the pyrazole arms in the topology of the resulting compounds. In the second part, the reactivity of the novel ligands L6-L8 against Pd(II) is assayed, and the results compared with those previously obtained with L4 and L5. In Section 3.4, the first coordination complexes containing N-alkylcarborane pyrazole ligands are described. In this work, a total of six coordination compound bearing L9-L11 and different metal centres (Cu(II), Zn(II), Cd(II), Hg(II) and Pd(II)) are described, allowing the observation of the effect of adding the carborane moiety to the pyrazole backbone. Section 3.5 describes the obtention of four luminescent Cu(I) compounds bearing ligands L9-L12. Some of them bear particularly rare motifs, and their obtention during the same work is remarkable. Moreover, the study of their luminescent behaviour has allowed us to investigate the emission processes in some scarcely studied compounds. These studies are backed by TDDFT calculations. In Chapter 4 the general conclusions of this work are presented. Moreover, for the sake of completeness, this work also contains and experimental section (Chapter 5) and an annex (Annex I) which contains all the spectra and additional information for this work. Finally, all the related publications for this work can be found in Annex IIUniversitat Autònoma de Barcelona. Programa de Doctorat en Químic