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The reaction of Ln(NO3)2·6H2O (Ln = Nd, Sm, Eu, Tb, Dy, Tm and Yb) with the respective enantiopure (R)-(−)-2-phenylbutyric or (S)-(+)-2-phenylbutyric acid (R/S-2-HPhBut) and 4,7-diphenyl-1,10-phenanthroline (Bphen) allows the isolation of chiral dinuclear compounds of the formula [Ln2(μ-R/S-2-PhBut)4(R/S-2PhBut)2(Bphen)2] where Ln = Nd3+ (R/S-Nd-a), Sm3+ (R/S-Sm-a), Eu3+ (R/S-Eu-a), Tb3+ (R/S-Tb-a and R/S-Tb-b), Dy3+ (R/S-Dy-a and R/S-Dy-b), Tm3+ (R/S-Tm-b) and Yb3+ (R/S-Yb-b). Single crystal X-ray diffraction was performed for compounds S-Eu-a and S-Tm-b. Powder crystal X-ray diffraction was performed for all complexes. From the crystallographic data two different structural motifs were found which are referred to as structure type a and structure type b. In structure type a, the Ln3+ atoms are bridged through four R or S-2-PhBut ligands with two different kinds of coordination modes whereas in structure type b the two Ln3+ atoms are bridged through four R or S-2-PhBut ligands showing only one kind of coordination mode. For those lanthanide ions exhibiting both structure types, Tb3+ and Dy3+, a difference in the luminescence and magnetism behavior is observed. All compounds (except R/S-Tm-b) exhibit sensitized luminescence, notably the Eu3+ and Tb3+ analogues. Circular Dichroism (CD) and Circular Polarized Luminescence (CPL) in the solid state and in 1 mM dichloromethane (DCM) solutions are reported, leading to improved chiroptical properties for the DCM solutions. The asymmetry factor (glum) in 1 mM DCM is ±0.02 (+ for R-Eu-a) for the magnetically allowed transition 5D0 → 7F1 and ±0.03 (+ for R-Tb-a and R-Tb-b) for the 5D4 → 7F5 transition. Magnetic properties of all compounds were studied and the Dy3+ compound with the structural motif b (R-Dy-b) shows Single Molecular Magnet (SMM) behavior under a 0 T magnetic field. However, R-Dy-a is a field-induced SMM. [ABSTRACT FROM AUTHOR]

Five new β-diketonate Ce3+ mononuclear complexes, [Ce(Btfa)3(H2O)2] (1), [Ce(Btfa)3(phen)] (2), [Ce(Btfa)3(bipy)] (3), [Ce(Btfa)3(terpy)] (4) and [Ce(Btfa)3(bathophen)(DMF)] (5), where Btfa− = 4,4,4-trifluoro-1-phenyl-1,3-butanedionate, phen = 1,10-phenanthroline, bipy = 2,2′-bipyridyl, terpy = 2,2′:6′,2′′-terpyridine and bathophen = 4,7-diphenyl-1,10-phenanthroline, have been synthesized and structurally characterized through X-ray diffraction of single crystals. The central Ce3+ atom displays a coordination number of 8 for 1, 2 and 3 and of 9 for 4 and 5. Under a 0 T external magnetic field, none of the given compounds exhibits single molecule magnet (SMM) behaviour. However, a small magnetic field, between 0.02 and 0.1 T, is enough for all the compounds to exhibit slow relaxation of the magnetization. A comprehensive magnetic analysis, with experimental magnetic data and ab initio calculations, was undertaken for all the complexes, and the study highlights the significance of the different spin relaxation mechanisms that must be considered for a Ce3+ lanthanide ion. [ABSTRACT FROM AUTHOR]

The reaction of [Ln(btfa)3(H2O)2] (btfa− = 4,4,4-trifluoro-1-phenyl-1,3-butanedionate) with 4,4′-dinonyl-2,2′-bipyridyl (4,4′-dinonylbipy) in ethanol allows isolation of mononuclear complexes [Ln(btfa)3(4,4′-dinonylbipy)] Ln = Sm (1-Sm), Eu (2-Eu), Tb (3-Tb), Dy (4-Dy), Er (5-Er) and Yb (6-Yb). The solid state luminescence emission in the visible region for 1-Sm, 2-Eu, 3-Tb and 4-Dy and in the NIR region for 1-Sm,5-Er and 6-Yb shows efficient energy transfer from the 4,4,4-trifluoro-1-phenyl-1,3-butanedionate ligands to the central Ln3+ ion for all the compounds. Finally, complexes 2-Eu and 6-Yb were successfully used as emitters in multilayer vacuum-deposited OLEDs. The electroluminescence quantum efficiency (EQE) of the corresponding devices reached 2.1% and ∼0.1–0.2% for 2-Eu (λEL = 614 nm) and 6-Yb (λEL = 977 nm), respectively. Maximum radiant emittance recorded for the Ln-associated emission achieved 135 μW cm−2 for 2-Eu and 121 μW cm−2 for 6-Yb. These values for efficiency and radiant emittance are unusually high for such type of emitters. Moreover, magnetic studies were performed on all compounds. Alternating current (AC) dynamic measurements indicated Single Molecular Magnet (SMM) behaviour for 4-Dy and field-induced slow relaxation of the magnetization for complexes 3-Tb, 5-Er and 6-Yb. The anisotropy energy barriers and pre-exponential factors are 91.1 cm−1, τ0 = 7.2 × 10−9 s (under zero magnetic field) and ΔE = 109.3 cm−1, τ0 = 9.3 × 10−10 s under 0.1 T magnetic field for 4-Dy and ΔE = 24.6 cm−1, τ0 = 8.7 × 10−8 s (under 0.07 T) for 5-Er. Besides, we observe that for compounds 3-Tb and 6-Yb the relaxation of the magnetization does not occur through the Orbach process. [ABSTRACT FROM AUTHOR]

The rational design of cocrystals triggered by the control of recurrent H-bonded patterns referred to as supramolecular synthons enabled the correlation between their structure and properties, which has been a topic of interest owing to the possibility to modulate them depending on the selected components. Accordingly, melting point has been one of the most studied properties, providing materials with enhanced thermal stability for specific applications. Within this frame, in this work we have selected a liquid and a solid pyridine derivative (dPy), namely 4-acetylpyridine (4-Acpy) and 2-hydroxypyridine (2-OHpy) to combine with carboxylic acids to obtain a pair of cocrystals. An initial virtual screening of some carboxylic acids based on the positive and negative critical points of the molecular electrostatic potential (MEP) surfaces was performed to evaluate the feasibility of cocrystal formation. This enabled us to select 1,3-benzodioxole-5-carboxylic acid (piperonylic acid, HPip) to combine with 4-Acpy and α-acetamidocinnamic acid (HACA) with 2-OHpy. Then, we have obtained the corresponding cocrystal experimentally by means of liquid-assisted grinding (LAG), and their crystal structures were elucidated, revealing the formation of (HPip)(4-Acpy) (1) and (HACA)(Pdon) (2) (Pdon = 2-pyridone), observing the tautomerization of 2-OHpy to Pdon. Both cocrystals were characterized by analytical and spectroscopic techniques. In addition, a Cambridge Structural Database (CSD) survey of 4-Acpy and Pdon in cocrystal systems was performed and the observed preferences regarding their preferable synthons and dimensionalities were shown. Finally, their melting points have been determined, and the resulting values have been correlated with the crystal packing of the compounds, supported by Hirshfeld surface analysis and energy frameworks. [ABSTRACT FROM AUTHOR]

Understanding the factors governing the self-assembly of organic ligands with metal ions is essential to engineering target molecular arrangements with the desired properties. Indeed, small modifications of the synthetic conditions lead to the obtention of different complexes, varying from discrete monomers to coordination polymers (CPs). Based on the potential coordinating ability of 2-furoic acid (2-FA), we prepared five Zn(II) and Cd(II) complexes to study the behavior of the furane O atom and the competitiveness of the M–O bond formation in methanol (MeOH). Reactions between M(OAc)2·2H2O (M = Zn(II), Cd(II)), 2-FA, and two p-substituted pyridine ligands (isonicotinamide (Isn) and 4-acetylpyridine (4-Acpy)) in MeOH yielded the two dimers [Zn(μ-2-FA)(2-FA)(Isn)2]2 (1) and [Cd(μ-2-FA)(2-FA)(Isn)2]2 (2), the dimeric paddle-wheel [Zn(μ-2-FA)2(4-Acpy)]2 (3), and the monomer [Cd(2-FA)2(4-Acpy)2(OH2)] (4). Their crystal structures have been studied, observing diverse coordination numbers between five and seven and diverse coordination modes of the carboxylate groups. Interestingly, the recrystallization of 4 in acetonitrile (ACN) resulted in a dissolution–recrystallization structural transformation (DRST), leading to an intricate coordination polymer (CP) with the formula {[Cd(μ-2-FA)(2-FA)(OH2)2]n[Cd(μ-2-FA)(2-FA)(4-Acpy)(OH2)]n} (5) exhibiting coordination of the furane O atom. Within this collection of arrangements, 2-FA displayed a great diversity of coordination modes that were combined and interchanged in the DRST process. Their photophysical properties in solution have been analyzed and their quantum yields calculated. Likewise, further insight into the DRST process was obtained from fluorescence measurements. From these results, a pathway for the structural transformation highlighting the crucial role of solvents has been proposed. [ABSTRACT FROM AUTHOR]

Enantiopure P-stereogenic methylphosphane-boranes (SP)-P(BH3)PhArMe (ArMe; Ar = 1-naphthyl (NpMe), and 2-biphenylyl (BiphMe)) have been used to prepare diphosphanes of the type ArPhPCH2PR2 (R = Ph, iPr or tBu; ArR). The ligands have been reacted with [Rh(COD)2]BF4 to furnish the corresponding six monochelated [Rh(COD)(ArR)]BF4 organometallic compounds (RhArR) or, depending on the reaction conditions, the bis(chelated) coordination compound [Rh(BiphiPr)2]BF4 as a mixture of cis and trans isomers. The crystal structure of cis-[Rh(BiphiPr)2]BF4 was obtained. The coordination of the BiphR with [RuCl(μ-Cl)(η6-p-cymene)2]2 under different conditions produced cationic chelated complexes of the type [RuCl(η6-p-cymene)(κ2-BiphR)]PF6 (RuBiphR) and the neutral monocoordinated complex [RuCl2(η6-p-cymene)(κ1-BiphPh)] (RuBiphPh′) with the uncoordinated P-stereogenic moiety. The Rh(I) complexes were used in the catalytic hydrogenation of functionalized olefins and the Ru(II) complexes were tested in the transfer hydrogenation of acetophenone. Both precursors displayed good activities with moderate enantioselectivities. [ABSTRACT FROM AUTHOR]

A new family of lanthanide compounds has been synthesized using 1,2-bis(diphenylphosphino)ethane dioxide (dppeO2) as an O-donor ligand through the phosphoryl group to lanthanide(III) cations and structurally, magnetically and optically studied. Depending on the lanthanide, two different topologies appear: the two-dimensional structure [LnIII(dppeO2)1.5(NO3)3(H2O)0.5]n (Ln = Ce (1), Sm (2) and Dy (6)) and the one-dimensional structure [Ln(dppeO2)(NO3)3DMF]n (Ln = Eu (3), Gd (4) and Tb (5)). Some of the Ln-derived complexes have been used as structural probes, while others have been synthesized to use the specific characteristics of each cation to take advantage of their magnetic/luminescence properties. Complex 6 presents slow relaxation of the magnetization while 2, 3 and 5 present emitting properties in the visible range. [ABSTRACT FROM AUTHOR]

Three azobenzenes CN(C6H4)-N＝N-(C5H4N) (py-iso), CN(C6H4)-N＝N-(C6H4)CN (cyano-iso) and CN(C6H4)-N＝N-(C6H4)NC (iso–iso) with good coordinating groups (pyridine, phenylcyano or phenylisocyano) at the ends of the diazenyl unit have been synthesized and fully characterised. These compounds have been used as ligands in the synthesis of water-soluble metallic species by coordination to {FeII(CN)53−} units, either in one or two of the anchoring groups of the derivatives. Both the azo derivatives and their complexes are photochemically active with respect to their trans-to-cis isomerisation process. Their cis-to-trans reverse thermal reaction has been thoroughly studied as a function of the donor groups, solvent, temperature and pressure, in order to gain insight into the rotation or inversion mechanisms involved in the process. A comparison of the isomerisation mechanism between the iron complexes and the corresponding free ligands revealed an interesting fine tuning of the process on coordination of the {FeII(CN)53−} moieties, which may even produce, in some cases, non-photoswitchable species containing typically photoactive units. [ABSTRACT FROM AUTHOR]

The reaction of Ln(NO3)2·6H2O (Ln = Eu, Tb, Dy and Sm) with (R)-(−)-α-methoxyphenylacetic acid (R-HMPA) and 1,10-phenanthroline (phen) in EtOH/H2O allows the isolation of 1D chiral compounds of formula [Ln(μ-R-MPA)(R-MPA)2(phen)]n in which Ln = Eu (R-Eu), Tb (R-Tb), Dy (R-Dy) and Sm (R-Sm). The same synthesis by using (S)-(+)-α-methoxyphenylacetic acid (S-HMPA) instead of (R)-(−)-α-methoxyphenylacetic acid allows the isolation of the enantiomeric compounds with formula [Ln(μ-S-MPA)(S-MPA)2(phen)]n where Ln = Eu (S-Eu), Tb (S-Tb), Dy (S-Dy) and Sm (S-Sm). Single crystal X-Ray diffraction measurements were performed for compounds R/S-Eu , R/S-Tb , S-Dy and S-Sm. The luminescence and the circular dichroism measured in the solid state are reported. All compounds show sensitized luminescence, notably the Eu3+ and Tb3+ ones, whose emission color can be perceived by the naked eye. For the Eu3+ and Tb3+ derivatives the quantum yield and the circular polarized luminescence have been measured. For the magnetic allowed transition 5D0 → 7F1 of the Eu3+ compound, the anisotropy factor glum is ±0.013 (+for S-Eu). Also, magnetic properties of all compounds were studied with the Dy3+ analogue showing slow relaxation of the magnetization under a direct current magnetic field of 1000 Oe. [ABSTRACT FROM AUTHOR]

A family of copper(II)/manganese(II) new clusters with the formulas [CuIINaI(L2)(MeOH)(ClO4)] (1), [Cu II2 MnII(S,S-L3)2(MeOH)](ClO4)2 (2SS), [{CuIIMnII(L1)(H2O)2(MeOH)}{CuII(L1)}2](ClO4)2 (3), [(μ1,3-N3)2{CuIIMnII(L2)(H2O)}2{CuII(L2)2](ClO4)}2 (4) and [(μ1,1-N3)2{CuIIMnII(L1)(N3)}2{CuIINaI(L1)(MeOH)}2](ClO4)2 (5) with L1 = N,N′-ethylene-bis(3-methoxysalicylaldiimine), L2 = N,N′-ethylene-bis(3-ethoxysalicylaldiimine) and L3 = N,N′-cyclohexane-bis(3-ethoxysalicylaldiimine), has been synthesized, and structurally and magnetically characterized. Reduced magnetization studies demonstrate that the magnetic anisotropy of the systems is very small. However, dynamic magnetic studies and ultra-low-frequency Raman spectroscopy confirm the slow relaxation of these systems despite their quasi-isotropic nature, enlarging the range of non-anisotropic slow relaxing molecules. [ABSTRACT FROM AUTHOR]

The formation of a new double-stranded staircase Hg(I) supramolecular assembly is reported. It is arranged into 2D corrugated sheets supported by Hg(I)⋯Odioxole and Hg⋯π interactions, resulting from the comproportionation reaction between Hg(II) and Hg(0) species in DMF as a solvent. [ABSTRACT FROM AUTHOR]

A new family of magnetically mononuclear cobalt(II) complexes with formula [{NiII(L)CoII(H2O)2(MeOH)}{NiII(L)}2](ClO4)2 where H2L1 = bis(N,N′-bis(3-methoxysalicylidene)ethylene-1,2-diamine) (1), H2L2 = bis(N,N'-bis(3-methoxysalicylidene)propane-1,2-diamine) (2) and [{CuII(L4)}2CoII](ClO4)2 (3) where H2L4 = bis(N,N′-bis(3-ethoxysalicylidene)cyclohexane-1,2-diamine) have been obtained employing non chiral or enantiomerically pure Schiff bases. The structural studies have been carried out by single crystal X-ray and powder diffraction. Dynamic magnetic studies indicate that some members of this family present field induced slow relaxation of the magnetization and its response has been compared with the magnetically diluted [Zn0.9Co0.1] complex 1D. Ultra-low frequency Raman spectroscopy has been used to relate the slow relaxation with lattice vibrations. [ABSTRACT FROM AUTHOR]

This work reports a combined computational and experimental analysis of the crystal structure of the cancer drug tipiracil hydrochloride in the form of a methanol solvate–hydrate (4 : 1 : 3, molar ratio). The crystal structure shows a complex network of H-bonds with static discrete disorder in two out of the three symmetry-independent solvent molecules, which has been studied by means of DVS and TGA techniques. MEP surface calculations shows a region of positive potential (σ-hole) along the C–Cl bond, which induces the formation of Cl⋯O contacts that are relevant in the crystal packing. The hydrogen and halogen bonding assemblies were further analyzed using density functional theory (DFT), the quantum theory of "atom-in-molecules" (QTAIM) and the noncovalent interaction plot (NCIplot). [ABSTRACT FROM AUTHOR]

Three field induced SMMs built from quasi-isotropic cations like CuII and MnII have been characterized, showing that relatively large clusters with quasi-negligible D and different ground spin states, S = 3/2, 2 or 4, can also exhibit field-induced slow relaxation of magnetization. [ABSTRACT FROM AUTHOR]

The reaction of Ln(NO3)2·6H2O salts (Ln = Eu and Tb) with an excess of 2-fluorobenzoic acid (H-2FBz) in an ethanol/water mixture allows the isolation of dinuclear compounds with the formula [Ln2(μ2-2FBz)4(2FBz)2(H-2FBz)2(H2O)2] (Ln = Eu (1) and Tb (2), 2FBz = 2-fluorobenzoate). A solid-state photoluminescence study of complexes 1 and 2 shows the 4f–4f lanthanide transitions in the visible range with improved emission quantum yields. 1 and 2 are water soluble and photoluminescence studies have also been performed in water and D2O solutions, showing that the emission due to the 4f–4f electronic transitions is still present. The magnetic behaviors of 1 and 2 are also reported. [ABSTRACT FROM AUTHOR]

Zn(II) complexes containing N, N,N and N,N,N pyridine (dPy) ligands tend to display improved fluorescence efficiencies in comparison with their starting ligands benefiting from the chelation enhanced effect (CHEF) and preventing photoinduced electron transfer (PET) mechanisms by the coordination of their lone pair electrons. Nevertheless, the size of Zn(II) makes steric crowding an important factor to be considered, since it can promote the elongation of the coordination bonds that weakens their strength and favors the reduction of fluorescence efficiencies through PET processes. For that reason, in this contribution we have performed a systematic study of Zn(II) compounds based on α-acetamidocinnamic acid (HACA) and a comprehensive range of dPy ligands with increasing bulkiness (pyridine (py) (1), 3-phenylpyridine (3-phpy) (2), 2,2′-bipyridine (2,2′-bipy) (3), 1,10-phenanthroline (1,10-phen) (4), 2,2′:6′,2′′-terpyridine (terpy) (5) and 4′-(4-methylphenyl)-2,2′:6′,2′′-terpyridine (mpterpy) (6)), which has allowed the equilibrium between CHEF and steric crowding effects to be studied. The elucidation of the six crystal structures revealed the formation of one coordination polymer (1) and five monomeric complexes (2–6). All of them have been characterized by analytical and spectroscopic techniques, and their molecular and supramolecular structures have been discussed. Furthermore, the UV-vis and photoluminescence properties have been recorded and their quantum yield (Φ) values have been calculated. Finally, it has been observed that even though the CHEF has a favorable impact on the fluorescence properties, the steric crowding of the ligands has been imposed, leading to fluorescence quenching. [ABSTRACT FROM AUTHOR]

A cocrystal screening conducted with solid solutions of three phytosterols (β-sitosterol, campesterol and stigmasterol) and a set of coformers with strong hydrogen bond donors reveals that multicomponent solid solutions are preferentially formed instead of pure cocrystals and are much enriched with β-sitosterol with respect to stigmasterol, a natural product with cytotoxicity concerns. [ABSTRACT FROM AUTHOR]

A wide family of clusters with the Na2Mn III6 LnIII core derived from an enantiomerically pure or a racemic mixture of Schiff bases lead to the characterization of a unique case of chiral/meso isomers with C3/D3d symmetry respectively, involving the rearrangement of the cluster bond parameters and the change from hepta- to hexacoordination of the central LnIII cation. [ABSTRACT FROM AUTHOR]