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A computational study on the interplay between ligand functionalization and guest effects on the transition temperature ( T 1/2 ) in the [Fe 2 (L 1 R ) 3 ]@X (L 1 = 1,3-bis-(3-(pyridin-2-yl)-1 H -pyrazol-5-yl)benzene, X = H - , F - , Cl - , Br - , I - and [BF 4 ] - , R = H, F, or CH 3 ) family of metal-organic cages (MOCs) is presented. Our results indicate that ligand functionalization with electron-donating or electron-withdrawing groups can significantly impact the T 1/2 as expected, while the guest effect in lowering the T 1/2 has a linear correlation with the increasing guest size. More importantly, small guests can move away from the center of the cavity, thus enhancing the two-step characteristic of the transition. All the data can be understood by analyzing the underlying electronic structure of the studied systems in terms of the relevant d-based molecular orbitals. These results can help in the rational design of new MOCs that can operate as sensors at specific temperatures, thus accelerating the discovery of new SCO devices with tailored properties.

Exploiting the potential of curcuminoids (CCMoids) as molecular platforms, a new 3.53 nm extended system (pyACCMoid, 2) has been designed in two steps by reacting a CCMoid with amino-terminal groups (NH 2 -CCMoid, 1, of 1.79 nm length) with polycyclic aromatic hydrocarbon (PAH) aldehydes. CCMoid 2 contains pyrene units at both ends as anchoring groups to optimize its trapping in graphene nano-junctions created by feedback-controlled electro-burning. The measured I - V characteristics show gate-dependent behaviour at room temperature and 10 K, with increased conductance values compared to shorter CCMoids previously reported, and in agreement with DFT calculations. Our results show that the adjusted molecular design improves the conductance, as system 2 separates the conductive backbone from the anchor groups, which tend to adopt a planar configuration upon contact with the graphene electrodes. DFT calculations using Green functions of a set of different molecular conformations of 2 on graphene electrodes show a direct relationship between the units ( e.g. pyrene, amide, etc. ), in the molecule, through which electrons are injected and the conductance values; where the size of the spacing between the graphene electrodes contributes but is not the dominant factor, and thus, counter-intuitively the smallest spacing gives one of the lowest conductance values., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

Singlet oxygen production and its reactivity have significant implications in fields ranging from polymer science to photodynamic therapy. Extensive research has focused on the development of organic-based materials and heavy metal complexes, including Ru(II), Rh(III), Ir(III) and Pt(II). However, metal complexes containing Au(I) have been scarcely explored and warrant further investigation. This review provides a comprehensive analysis of reported compounds, classified based on the ligands coordinated to the gold(I) centre. Additionally, future directions in photosensitizer development and singlet oxygen applications are discussed.

The reaction of Ln(NO 3 ) 2 ·6H 2 O (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 [Ln 2 (μ- R / S -2-PhBut) 4 ( R / S -2PhBut) 2 (Bphen) 2 ] where Ln = Nd 3+ (R/S-Nd-a), Sm 3+ (R/S-Sm-a), Eu 3+ (R/S-Eu-a), Tb 3+ (R/S-Tb-a and R/S-Tb-b), Dy 3+ (R/S-Dy-a and R/S-Dy-b), Tm 3+ (R/S-Tm-b) and Yb 3+ (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 Ln 3+ 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 Ln 3+ 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, Tb 3+ and Dy 3+ , a difference in the luminescence and magnetism behavior is observed. All compounds (except R/S-Tm-b) exhibit sensitized luminescence, notably the Eu 3+ and Tb 3+ 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 ( g lum ) in 1 mM DCM is ±0.02 (+ for R-Eu-a) for the magnetically allowed transition 5 D 0 → 7 F 1 and ±0.03 (+ for R-Tb-a and R-Tb-b) for the 5 D 4 → 7 F 5 transition. Magnetic properties of all compounds were studied and the Dy 3+ 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.

The synthesis of three novel [C,N,N'] Pt(IV) cyclometallated compounds containing hydroxo, dichloroacetato or trifluoroacetato axial ligands is reported. Compound [PtCl(OH) 2 {(CH 3 ) 2 N(CH 2 ) 2 NCH(4-FC 6 H 3 )}] (3) was prepared by the oxidative addition of hydrogen peroxide to [C,N,N'] Pt(II) cyclometallated compound [PtCl{(CH 3 ) 2 N(CH 2 ) 2 NCH(4-FC 6 H 3 )}] (1) and further the reaction of compound 3 with dichloroacetate or trifluoroacetate anhydrides led to the formation of the corresponding compounds [PtCl(CHCl 2 COO) 2 {(CH 3 ) 2 N(CH 2 ) 2 NCH(4-FC 6 H 3 )}] (4) and [PtCl(CF 3 COO) 2 {(CH 3 ) 2 N(CH 2 ) 2 NCH(4-FC 6 H 3 )}] (5). The properties of the new compounds along with those of the compound [PtCl 3 {(CH 3 ) 2 N(CH 2 ) 2 NCH(4-FC 6 H 3 )}] (2), including stability in aqueous media, reduction potential using cyclic voltammetry, cytotoxic activity against the HCT116 CRC cell line, DNA interaction, topoisomerase I and cathepsin inhibition, and computational studies involving reduction of the Pt(IV) compounds and molecular docking studies, are presented. Interestingly, the antiproliferative activity of these compounds against the HCT116 CRC cell line, which is in all cases higher than that of cisplatin, follows the same trend as the reduction potentials so that the most easily reduced compound 2 is the most potent. In contrast, according to the electrophoretic mobility and molecular docking studies, the efficacy of these compounds in binding to DNA is not related to their cytotoxicity. The most active compound 2 does not modify the DNA electrophoretic mobility while the less potent compound 3 is the most efficient in binding to DNA. Although compounds 2 and 3 have only a slight effect on cell cycle distribution and apoptosis induction, generation of ROS to a higher extent for the most easily reduced compound 2 was observed.

Two new paramagnetic supramolecular helicates with the formula (X@[Ni 2 L 3 ]) 3+ (X = Cl, or Br; L = a bis-pyrazolylpyridine ligand) have been prepared and are described. Helicates of this metal are very rare with virtually no prior examples of them acting as hosts of anionic species. The persistence of the new assemblies in solution has been demonstrated unambiguously by mass spectrometry and paramagnetic 1 H NMR. This has allowed us to establish the preference of the coordination [Ni 2 ] host for Cl - over Br - , in agreement with DFT calculations. These results show the promise of the use of metallohelicates as suitable systems for the selective encapsulation of specific anions in solution.

The energy difference between different spin states of systems with transition metals is an outstanding challenge for electronic structure calculation methods. The small energy difference between high- and low-spin states in spin-crossover systems makes most post-Hartree-Fock or density functional theory-based methods provide inaccurate values. A test case of twenty systems showing spin transitions has been used to evaluate the accuracy of a new family of training meta -GGA (Generalized Gradient Approximation) functionals. One of the functionals of this new family provides comparable or even better values than the best functional reported so far for this type of system, the TPSSh hybrid meta -GGA functional, but without having to use the exact exchange term. It also improves the results obtained with the r 2 SCAN meta -GGA functional, which was the best alternative to the TPSSh hybrid functional. This makes it possible to calculate the spin energetics of any kind of compound, especially large systems or periodic structures where the exact exchange requires large computational resources.

A new mononuclear iron(II) SCO compound featuring H-bonding donor and acceptor units has been synthesized and exploited to produce a purely supramolecular switchable [Fe 4 ] tetrahedron. Magnetic and crystallographic measurements evidence a singular magnetic behavior for each of the four Fe(II) centers of the generated architecture and underscore the potential of this strategy to develop novel SCO materials.

Five new β-diketonate Ce 3+ mononuclear complexes, [Ce(Btfa) 3 (H 2 O) 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 Ce 3+ 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 Ce 3+ lanthanide ion.

A new doubly carboxylato-bridged Co(II) dinuclear complex, [Co(bdtbpza)(NCS)] 2 (1), was obtained in a satisfactory yield by employing a 'scorpionate'-type precursor, bdtbpza {bis-(3,5-di- tert -butylpyrazol-1-yl)acetate}, and was then structurally characterized. Single-crystal X-ray diffraction analysis revealed that, in 1, each Co(II) is penta-coordinated, leading to a distorted trigonal-bipyramidal geometry within the coordination environment of N 3 O 2 . Weak antiferromagnetic coupling within the Co(II) ions in 1 was found based on the isotropic spin Hamiltonian H = - J ( S 1 · S 2 ) for the S i = 3/2 system. For evaluating the spin density distribution and the mechanism for the magnetic exchange coupling, DFT analysis was performed, with the calculated result agreeing the experimental magnetic data. A study into electrochemical H 2 evolution, involving cyclic voltammetry (CV), controlled potential electrolysis (CPE), and gas chromatographic (GC) analyses of the graphite electrode modified with the cobalt complex in a neutral aqueous solution revealed the high catalytic activity of the complex with a low overpotential toward H 2 O reduction. The faradaic efficiency of the catalyst was found to be 83.7% and the di-cobalt catalyst-modified electrode displayed quite an interesting H 2 -evolution activity compared with that of bare electrodes. These results are encouraging for the future potential application of 1 in water splitting.

Three new hetero-metallic Cu II -Ln III complexes [(CuL)Gd(NO 3 ) 3 (CH 3 OH)] n (1), [(CuL)Tb(NO 3 ) 3 (H 2 O)]·[CuL] (2) and [(CuL)Dy(NO 3 ) 3 (H 2 O)]·[CuL] (3) have been synthesized using a mono-nuclear Cu(II) complex, [CuL], of an unsymmetrically di-condensed N 2 O 3 donor Schiff base ligand, N -(3-methoxysalicylidene)- N -(salicylidene)-1,2-ethylenediamine (H 2 L). Single crystal X-ray crystallography revealed that complex 1 is a nitrate bridged 1D chain of dinuclear Cu(II)-Gd(III) units whereas in 2 and 3, the dinuclear Cu(II)-Ln(III) units are co-crystallized with a [CuL] unit. The Ln(III) centers are nine coordinated with the geometry of a spherical capped square antiprism for Gd and spherical tricapped trigonal prism for Tb and Dy. The geometry of the Cu(II) center is distorted octahedral for complex 1 and distorted square planar for complexes 2 and 3. Temperature-dependent molar magnetic susceptibility measurements in 1-3 revealed the presence of overall ferromagnetic coupling between the Cu(II) and Ln(III) centers. Notably, field induced single-molecule magnet behavior was witnessed in the Tb(III) derivative (2). The ab initio calculations indicated that upon application of an external magnetic field, the tunneling in the ground state of complex 2 gets reduced and thereby field-induced SMM behaviour is observed. Besides, in the case of complex 1, BS-DFT calculations were carried out to gain further insights into the magnetic exchange coupling interactions between the Cu(II) and Gd(III) centers.

Ditopic bis-pyrazolylpyridine ligands usually react with divalent metal ions (M 2+ ) to produce dinuclear triple-stranded helicates [M 2 L 3 ] 4+ or, via π⋯π interactions, dimers of monoatomic complexes ([ML 3 ] 2 ) 4+ . The introduction of an additional benzene ring at each end of ligand L increases the number of aromatic contacts within the supramolecular aggregate by 40%, driving the self-recognition process in an irreversible manner. Consequently, the mixing of new bis-pyrazolylquinoline L2 with FeX 2 salts leads to crystallization of the tripartite high-spin assemblies (X@[Fe(L2) 3 ] 2 ) 3+ (X = Cl, Br or I). The aggregates exhibit exceptional stability, as confirmed by a combination of paramagnetic 1 H NMR techniques, demonstrating their persistence in solution. Our investigations further reveal that the guests Br - and I - are retained inside the associate in solution but Cl - is immediately released, resulting in the formation of the empty supramolecular dimer ([Fe(L2) 3 ] 2 ) 4+ ., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The paper reports on the synthesis, crystal structure, thermal and magnetic properties of spin crossover (SCO) salts containing the [Fe(bpp) 2 ] 2+ cation (bpp = 2,6-bis(pyrazol-3-yl)pyridine) and different rigid polycarboxylate anions, such as anthracene-9,10-dicarboxylate (ADC), benzene-1,3,5-tricarboxylate (BTC) and biphenyl-4,4'-dicarboxylate (BPDC). Compound [Fe(bpp) 2 ](ADC)·9H 2 O (1) shows a porous hydrogen-bonded structure with water molecules sitting in the channels. It contains low-spin (LS) Fe 2+ cations that undergo crossover to the high-spin (HS) state upon dehydration. Anhydrous 1 remains HS on cooling at low temperatures. A similar magnetic behaviour is obtained for the partially protonated BTC salt [Fe(bpp) 2 ](HBTC)·5H 2 O (2), showing a spin change concomitant with dehydration to a HS phase that undergoes gradual and partial SCO on cooling, affecting 25% of the Fe 2+ cations. Instead, the BPDC salt [Fe(bpp) 2 ](BPDC)·5H 2 O (3) has a ground HS state in its fully hydrated form.

Coordination supramolecular chemistry provides a versatile entry into materials with functionalities of technological relevance at the nanoscale. Here, we describe how two different bis-pyrazolylpyridine ligands (L1 and L2) assemble with Co(II) ions into dinuclear triple-stranded helicates, in turn, encapsulating different anionic guests. These constructs are described as (Cl@[Co 2 (L1) 3 ]) 3+ , (SiF 6 @[Co 2 (L1)(L2) 3 ]) 2+ and (ClO 4 @[Co 2 (L2) 3 ]) 3+ , as established by single-crystal X-ray diffraction. Extensive magnetic and calorimetric measurements, numerical treatments and theoretical calculations reveal that the individual Co(II) centers of these supramolecular entities exhibit field-induced slow relaxation of magnetization, dominated by direct and Raman mechanisms. While the small variations in the spin dynamics are not easily correlated with the evident structural differences among the three species, the specific heat measurements suggest two vibronic pathways of magnetic relaxation: one that would be associated with the host lattice and another linked with the guest.

Non-frontier atom exchanges in hydrogen-bonded aromatic dimers can induce significant interaction energy changes (up to 6.5 kcal mol -1 ). Our quantum-chemical analyses reveal that the relative hydrogen-bond strengths of N -edited guanine-cytosine base pair isosteres, which cannot be explained from the frontier atoms, follow from the charge accumulation in the monomers.

A three-dimensional terbium(III) coordination polymer of formula [Tb(bttb) 0.5 (2,5-pzdc) 0.5 ] n (1) [H 4 bttb = 1,2,4,5-tetrakis(4'-carboxyphenyl)benzene and H 2 -2,5-pzdc = 2,5-pyrazinedicarboxylic acid] was obtained under hydrothermal conditions. The bttb 4- tetraanion in 1 adopts the bridging and chelating-bridging pseudo-oxo coordination modes while the 2,5-pzdc 2- dianion exhibits a rather unusual bis-bidentate bridging pseudo-oxo coordination mode, both ligands being responsible for the stiffness of the resulting 3D structure. Solid-state photoluminescent measurements illustrate that 1 exhibits remarkable green luminescence emission, the most intense band occurring in the region of 550 nm ( 5 D 4 → 7 F 5 ) with lifetimes at the millisecond scale. Thermometric performances of 1 reveal a maximum relative sensitivity ( S m ) of 0.76% K -1 at 295 K (δ T = 0.05 K), constituting a Tb III ratiometric solid luminescent thermometer over the physiological temperature range. Variable-temperature static (dc) magnetic susceptibility measurements for 1 in the temperature range 2.0-300 K show the expected behavior for the depopulation of the splitted m J levels of the 7 F 7 ground state of the magnetically anisotropic terbium(III) ion plus a weak antiferromagnetic interaction through the carboxylate bridges. No significant out-of-phase magnetic susceptibility signals were observed for 1 in the temperature range 2.0-10.0 K, either in the absence or presence of a static dc magnetic field.

The coordinated azido ligand has a variety of ways to establish intermolecular contacts whose nature is computationally analysed in this work on dimers of the [N 3 -Hg(CF 3 )] complex with different interactions involving only N⋯N contacts, or with an additional Hg⋯N contact. The applied tools include the molecular electrostatic map of the monomer, an energy decomposition analysis (EDA), a topological AIM analysis of the electron density and the study of NCI (non-covalent interactions) isosurfaces. The interactions between two azido ligands are found to be weakly stabilizing (by 0.2 to 2.7 kcal mol -1 ), topology-dependent and require dispersion forces to complement orbital and electrostatic stabilization. Those interactions are supplemented by the formation of simultaneous Hg⋯N secondary interactions by about -1 kcal mol -1 , and by the ability of the monomer to simultaneously interact with several neighbours in the crystal structure.

Twelve (N^N^N)platinum pyridyl complexes, (N^N^N)Pt(pyF), were synthesised and investigated for their singlet oxygen generation and potential biological activities. They exhibited 1 IL and 1 MLCT absorption transitions at approximately 325 and 360 nm, identified through TD-DFT calculations. Luminescence was observed only in the L1-derived compounds in solution, with a dual emission with the main contribution of phosphorescence under deaerated conditions. Room temperature phosphorescence was detected in all solid-state cases. Electron-withdrawing substituents at specific positions (R1 and X) and the number of fluorine atoms in R2 were found to enhance the photosensitizing capabilities of these compounds. Biological assessments, including cytotoxicity and photocytotoxicity, were conducted to evaluate their potential as chemotherapeutic agents and photosensitizers. Complexes with chloro substitution in the N^N^N tridentate ligand of the central pyridine ring exhibited promising chemotherapeutic properties. Ancillary pyridine ring substitution became significant under irradiation conditions, with fluoromethylated substituents enhancing cytotoxicity. Complex 2-CF3 was the most efficient singlet oxygen producer and a highly effective photosensitizer. CHF 2 -substituted complexes also showed improved photosensitizing activity. DNA binding studies indicated moderate interactions with DNA, offering insights into potential biological applications.

Among the multiple applications of metal-organic frameworks (MOFs), their use as a porous platform for the support of metallic nanoparticles stands out for the possibility of integrating a good anchorage, that improves the stability of the catalyst, with the presence of a porous network that allows the diffusion of substrates and products. Here we introduce an alternative way to control the injection of Au nanoparticles at variable stages of nucleation of a titanium(iv) MOF crystal (MUV-10). This allows the analysis of the different modes of nanoparticle integration into the porous matrix as a function of the crystal formation stage and their correlation with the catalytic performance of the resulting composite. Our results reveal a direct effect of the stage at which the Au nanoparticles are integrated into MUV-10 crystals not only on their catalytic activity for the cyclotrimerization of propargyl esters and the hydrochlorination of alkynes, but also on the selectivity and recyclability of the final solid catalyst, which are far superior than those reported for the same reactions with TiO 2 supports., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A family of heteroleptic spin crossover (SCO) [Fe III (qsal-5-I)(qsal-5-OMe)]A·sol (qsal-5-X = 5-X-2-[(8-quinolylimino)methyl]phenolate; A = NO 3 - 1 sol = 2MeOH, NCS - 2 sol = 0.75MeOH·1.3H 2 O, BF 4 - 3 sol = MeOH, OTf - 4, sol = MeOH) complexes have been synthesized. Most of the complexes exhibit gradual SCO, with the exception of NCS, which is principally high spin. In contrast, the OTf complex shows an abrupt hysteretic SCO (35 K) after solvent loss. The magnetic properties of this complex are significantly improved in comparison to the related homoleptics, [Fe(qsal-I) 2 ]OTf 5 (hysteresis, 8 K) and [Fe(qsal-5-OMe) 2 ]OTf·CH 2 Cl 2 6 (gradual SCO). Structural studies reveal that slight changes in the crystal packing cause stronger interactions improving the cooperativity. These findings are supported by DFT calculations using the r 2 SCAN functional in which the calculated structures show that SCO from the LS to the HS state causes pronounced scissoring of the 1D π-π chains and substantial changes in their relative orientation following loss of MeOH.

Host-guest chemistry within the confined space of metal-organic frameworks (MOFs) offers an almost unlimited myriad of possibilities, hardly accessible with other materials. Here we report the synthesis and physical characterization, with atomic resolution by single-crystal X-ray diffraction, of a novel water-stable tridimensional MOF, derived from the amino acid S -methyl-L-cysteine, {SrZn 6 [( S , S )-Mecysmox] 3 (OH) 2 (H 2 O)}·9H 2 O (1), and its application as a robust and efficient solid catalyst for the cycloaddition reaction of ethylene/propylene oxide with CO 2 to afford ethylene/propylene carbonate with yields of up to 95% and selectivity of up to 100%. These results nicely illustrate the great potential of MOFs to be game changers for the selective synthesis of industrially relevant products, representing a powerful alternative to the current heterogeneous catalysts.

Class I inverting exo-acting α-1,2-mannosidases (CAZY family GH47) display an unusual catalytic itinerary featuring ring-flipped mannosides, 3 S 1 → 3 H 4 ‡ → 1 C 4 . Conformationally locked 1 C 4 compounds, such as kifunensine, display nanomolar inhibition but large multigene GH47 mannosidase families render specific "isoform-dependent" inhibition impossible. Here we develop a bump-and-hole strategy in which a new mannose-configured 1,6- trans -cyclic sulfamidate inhibits α-d-mannosidases by virtue of its 1 C 4 conformation. This compound does not inhibit the wild-type GH47 model enzyme by virtue of a steric clash, a "bump", in the active site. An L310S (a conserved residue amongst human GH47 enzymes) mutant of the model Caulobacter GH47 awoke 574 nM inhibition of the previously dormant inhibitor, confirmed by structural analysis of a 0.97 Å structure. Considering that L310 is a conserved residue amongst human GH47 enzymes, this work provides a unique framework for future biotechnological studies on N -glycan maturation and ER associated degradation by isoform-specific GH47 α-d-mannosidase inhibition through a bump-and-hole approach., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Plastic phases are constituted by molecules whose centers of mass form a long range ordered crystalline lattice, but rotate in a more or less constrained way. Pentachloronitrobenzene (PCNB) is a quasi-planar hexa-substituted benzene formed by a benzene ring decorated with a -NO 2 group and five chlorine atoms that displays below the melting point a layered structure of rhombohedral ( R 3̄) planes in which the molecules can rotate around a six-fold-like axis. Dielectric spectroscopy [Romanini et al. , The Journal of Physical Chemistry C , 2016, 120 , 10614] of this highly anisotropic phase revealed a complex relaxation dynamics with two coupled primary α processes, initially ascribed to the in-plane and out-of-plane components of the molecular dipole. In this work, we perform a series of molecular dynamics simulations together with single crystal X-ray synchrotron diffraction experiments to investigate the puzzling dynamics of PCNB. We conclude that the molecule undergoes very fast movements due to the high flexibility of the -NO 2 group, and two slower movements in which only the in-plane rotation of the whole ring is involved. These two movements are related to fast attempts to perform a 60° in-plane rotation, and a diffusive motion that involves the rotation of the molecule completely decorrelating the dipole orientation. We have also investigated whether a homogeneous or a heterogeneous scenario is better suited to describe the restricted orientational disorder of this anisotropic phase both from a structural and dynamical point of view.

With their distinctive physicochemical features, nanoparticles have gained recognition as effective multifunctional tools for biomedical applications, with designs and compositions tailored for specific uses. Notably, magnetic nanoparticles stand out as first-in-class examples of multiple modalities provided by the iron-based composition. They have long been exploited as contrast agents for magnetic resonance imaging (MRI) or as anti-cancer agents generating therapeutic hyperthermia through high-frequency magnetic field application, known as magnetic hyperthermia (MHT). This review focuses on two more recent applications in oncology using iron-based nanomaterials: photothermal therapy (PTT) and ferroptosis. In PTT, the iron oxide core responds to a near-infrared (NIR) excitation and generates heat in its surrounding area, rivaling the efficiency of plasmonic gold-standard nanoparticles. This opens up the possibility of a dual MHT + PTT approach using a single nanomaterial. Moreover, the iron composition of magnetic nanoparticles can be harnessed as a chemotherapeutic asset. Degradation in the intracellular environment triggers the release of iron ions, which can stimulate the production of reactive oxygen species (ROS) and induce cancer cell death through ferroptosis. Consequently, this review emphasizes these emerging physical and chemical approaches for anti-cancer therapy facilitated by magnetic nanoparticles, combining all-in-one functionalities.

Cooperative effects cause extra stabilization of hydrogen-bonded supramolecular systems. In this work we have designed hydrogen-bonded rosettes derived from a guanine-cytosine Janus-type motif with the aim of finding a monomer that enhances the synergy of supramolecular systems. For this, relativistic dispersion-corrected density functional theory computations have been performed. Our proposal involves a monomer with three hydrogen-bonds pointing in the same direction, which translates into shorter bonds, stronger donor-acceptor interactions, and more attractive electrostatic interactions, thus giving rise to rosettes with strengthened cooperativity. This newly designed rosette has triple the cooperativity found for the naturally occurring guanine quadruplex.

The reaction of three [Fe II (TSC) 2 ] complexes, where TSC is a pyridine-substituted thiosemicarbazone of the HDpT or HBpT families, with H 2 O 2 in acetonitrile solution does not result in the accumulation of the corresponding [Fe III (TSC) 2 ] + complexes. Instead, a mixture of diamagnetic low-spin Fe II species is generated. According to the MS spectra, those species result from the sequential addition of up to five oxygen atoms to the complex. This capability for the addition of oxygen atoms suggested that oxygen atom transfer to external substrates may be possible, and these TSC complexes were tested in the oxidation of thioanisole and styrene with H 2 O 2 . As hypothesized, the complexes are active in both the oxidation of thioanisole to its sulfoxide and styrene to benzaldehyde, with time scales indicating the participation of the species containing added oxygen atoms. Interestingly, the free thiosemicarbazone ligands and the [Zn(Dp44mT) 2 ] complex also catalyse the selective sulfoxidation of thioanisole, but they are ineffective in catalysing styrene oxidation to benzaldehyde. These findings open up new directions for the development of thiosemicarbazone-based metal catalysts for oxidation processes.

The chelator diacetyl-bis( N 4-methylthiosemicarbazone) (ATSM) and its complexes with Cu II and Zn II are becoming increasingly investigated for medical applications such as PET imaging for anti-tumour therapy and the treatment of amyotrophic lateral sclerosis. However, the solubility in water of both the ligand and the complexes presents certain limitations for in vitro studies. Moreover, the stability of the Cu II and Zn II complexes and their metal exchange reaction against the potential biological competitor human serum albumin (HSA) has not been studied in depth. In this work it was observed that the ATSM with an added carboxylic group into the structure increases its solubility in aqueous solutions without altering the coordination mode and the conjugated system of the ligand. The poorly water-soluble Cu II - and Zn II -ATSM complexes were prevented from precipitating due to the binding to HSA. Both HSA and ATSM show a similar thermodynamic affinity for Zn II . Finally, the Cu II -competition experiments with EDTA and the water-soluble ATSM ligands yielded an apparent log  K d at pH 7.4 of about -19. When ATSM was added to Cu II - and Zn II -loaded HSA, withdrawing of Zn II was kinetically favoured, but this metal is slowly substituted by the Cu II afterwards taken from HSA so that this protein could be considered as a source of Cu II for ATSM.

A biphenyl-spaced bis-pyrazolylpyridine ligand interacts with ferrous ions to engender a dimetallic helical coordination cage that encapsulates an Fe 3+ tris-anilate complex. The host-guest interaction breaks the symmetry of the Fe 2+ centers causing a differential spin crossover behavior in them that can be followed in great detail crystallographically.

A reaction between CoCl 2 and L 3 -(CO 2 - ) 2 (2 : 1 stoichiometry) in CH 3 OH affords a discrete complex [CoII4-{L 3 -(CO 2 - ) 2 } 2 (μ 3 -OCH 3 ) 2 (CH 3 OH) 2 (H 2 O) 2 Cl 2 ] (1) [L 3 -(CO 2 - ) 2 = 3-[ N -{2-(pyridin-2-yl)methyl}amino]-bis(propionate)]. The structure of 1 reveals two terminal mononuclear Co II {L 3 -(CO 2 - ) 2 }Cl units connected by a dimeric CoII2(μ 3 -OCH 3 ) 2 (CH 3 OH) 2 (H 2 O) unit present in the centre through two methoxo (μ 3 -OCH 3 )- and two carboxylate (μ-1,1-OCO-) bridges affording a tetranuclear coordination cluster of Co(II) with a defective dicubane topology. In 1, Co1 (terminal) has distorted octahedral Co II N 2 O 3 Cl and the central Co2 has Co II O 6 coordination. Such coordination arrangements afford the observed topology. Variable-temperature magnetic studies reveal anti-ferromagnetic coupling in 1. Three magnetic exchange interactions (one anti-ferromagnetic and two ferromagnetic: J 1 = +3.3 cm -1 (Co⋯Co 3.176 Å; μ-1,1-OCO- and μ 3 -OCH 3 bridges), J 2 = -2.5 cm -1 (Co⋯Co 3.228 Å; μ-1-OCO- and μ 3 -OCH 3 bridges) and J 3 = +10.6 cm -1 (Co⋯Co 3.084 Å; two μ 3 -OCH 3 bridges)) have been identified, with the inclusion of the orbital reduction parameter ( α = Aκ = 1.38), spin-orbit coupling ( λ = -158 cm -1 ) and axial distortion (energy gap Δ = -975 cm -1 between singlet and doublet levels), rationalized by density functional theory (DFT) calculations.

Five metal-arene complexes of formula [MX 2 (η 6 - p -cymene)(diR(1-pyrenyl)phosphane)] (M = Os or Ru, X = Cl or I, R = isopropyl or phenyl) and symbolized as MRX2 were synthesized and fully characterized, namely OsiPrCl2 , OsiPrI2 , OsPhCl2 , OsPhI2 and RuPhI2 . Furthermore, nine cyclometalated half-sandwich complexes of formula [MX-(η 6 - p -cymene)( k 2 C-diR(1-pyrenyl)phosphane)] (M = Os or Ru, X = Cl or I, R = isopropyl or phenyl) or [M(η 6 - p -cymene)( k S-dmso)( k 2 C-diR(1-pyrenyl)phosphane)]PF 6 (M = Os or Ru, R = isopropyl or phenyl) and symbolized as c-MRX were prepared; hence, c-OsiPrCl , c-OsiPrI , c-OsiPrdmso , c-OsPhCl , c-OsPhI , c-OsPhdmso , c-RuPhCl , c-RuPhI and c-RuPhdmso were obtained and fully characterized. The crystal structures of ten out of the fourteen complexes were solved. All complexes exhibit notable cytotoxic properties against A549 (Lung Adenocarcinoma) human cells, with IC 50 values ranging from 48 to 1.42 μM. In addition, complex c-OsiPrdmso shows remarkable toxic behaviours agains other cell lines, namely MCF7 (breast carcinoma), MCF10A (non-tumorigenic epithelial breast) and MDA-MB-435 (melanoma) human cells, as illustrated by IC 50 values of 4.36, 4.71 and 2.32 μM, respectively. Finally, it has been found that OsiPrI2 affects the cell cycle of A549 cells, impeding their replication ( i.e. , the cell cycle is blocked), whereas OsPhI2 (namely with phenyl groups instead of isopropyl ones) does not induce this effect.

Photodynamic therapy (PDT) represents a promising approach for cancer treatment. However, the oxygen dependency of PDT to generate reactive oxygen species (ROS) hampers its therapeutic efficacy, especially against hypoxic solid tumors. In addition, some photosensitizers (PSs) have dark toxicity and are only activatable with short wavelengths such as blue or UV-light, which suffer from poor tissue penetration. Herein, we developed a novel hypoxia-active PS with operability in the near-infrared (NIR) region based on the conjugation of a cyclometalated Ru(ii) polypyridyl complex of the type [Ru(C^N)(N^N) 2 ] to a NIR-emitting COUPY dye. The novel Ru(ii)-coumarin conjugate exhibits water-solubility, dark stability in biological media and high photostability along with advantageous luminescent properties that facilitate both bioimaging and phototherapy. Spectroscopic and photobiological studies revealed that this conjugate efficiently generates singlet oxygen and superoxide radical anions, thereby achieving high photoactivity toward cancer cells upon highly-penetrating 740 nm light irradiation even under hypoxic environments (2% O 2 ). The induction of ROS-mediated cancer cell death upon low-energy wavelength irradiation along with the low dark toxicity exerted by this Ru(ii)-coumarin conjugate could circumvent tissue penetration issues while alleviating the hypoxia limitation of PDT. As such, this strategy could pave the way to the development of novel NIR- and hypoxia-active Ru(ii)-based theragnostic PSs fuelled by the conjugation of tunable, low molecular-weight COUPY fluorophores., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

We present the synthesis, through a simple, microwave-assisted method, of lanthanoid-based 2D metal-organic frameworks (MOFs) of general formula [Ln x Ln' 1- x (MeCOO)(PhCOO) 2 ], including homonuclear compounds ( x = 1), LnEu, Tb, and heterometallic compounds, [TbEu]. The crystalline material is formed by neutral nanosheets held together by van der Waals interactions, which can be easily exfoliated by sonication. Photoluminescent emission in the visible range was observed for all of the synthesized 2D MOF compounds via excitation of the ligand, showing benzoates are efficient antenna ligands. Efficient energy transfer from Tb → Eu was observed in the heterometallic [TbEu] compounds, which could potentially perform as luminescent thermometers. Inks containing nanosheets of 2D MOFs exfoliated in solution were prepared, and luminescent prints of Tb and Eu 2D MOFs on paper were made to show the possible application for anticounterfeiting. Frequency-dependent ac susceptibility results show the occurrence of slow magnetic relaxation in [TbEu] compounds through direct relaxation mechanisms, affected by bottleneck effect. A slowing down of the relaxation time is observed as the Eu/Tb ratio increases.

Exploring the chemical space of a given ligand aiming to modulate its ligand field strength is a versatile strategy for the fine-tuning of physical properties such as the transition temperature ( T 1/2 ) of spin-crossover (SCO) complexes. The computational study presented herein aims at systematically exploring the extent to which the ligand substituent effects can modulate T 1/2 in two families of Fe(III) SCO systems with a N 4 O 2 coordination environment and at identifying the best descriptors for fast and accurate prediction of changes in T 1/2 upon ligand functionalization. B3LYP* calculations show that the attachment of substituents to β-ketoiminato fragments (L 1 ) leads to drastic changes in T 1/2 , while functionalization of phenolato moieties (L 2 ) allows for a finer degree of control over T 1/2 . Natural Bond Orbital (NBO) charges of the donor atoms, Hammett parameters for both para and meta -functionalization of L 2 , and Swain-Lupton parameters for L 1 and para -functionalization of L 2 have been found to be the suitable descriptors for predicting the changes in T 1/2 . Further analysis of the ligand-field splitting in such systems rationalizes the observed trends and shows that ligand substituents modify both the σ and π bonds between the Fe(III) center and the ligands. Thus, we provide simple yet reliable guidelines for the rational design of new SCO systems with specific values of T 1/2 based on their ligand design.

Indolizines and their saturated derivatives are important structural motifs present in several biologically active compounds of both natural and synthetic origin. We describe herein a one-pot approach for the synthesis of tricyclic indolizines catalyzed by a bicyclic imidazole-alcohol. The protocol is based on an aqueous Morita-Baylis-Hillman reaction between pyridine-2-carboxaldehydes and six- or seven-membered cyclic enones, followed by sequential intramolecular cyclization and dehydration. So, in a single operational step two new bonds (C-C and C-N) are formed in an organocatalyzed process that takes place in simple conditions (stirring in water at 60 °C for 12 h) and with great atom economy (water as the sole byproduct), affording the purified compounds in yields ranging from 19 to 70%. The facility of the cyclization strongly depends on the size of the cycloalkenone ring: while MBH adducts derived from six-, seven- or eight-membered cycloenones are readily transformed into the corresponding indolizines, cyclopentenone-derived MBH adducts do not cyclize. A competition experiment revealed that cycloheptenone-derived MBH adducts cyclize faster than cyclohexenone-derived adducts. Model DFT calculations have been performed to rationalize these reactivity trends.

The uptake and release of small molecules continue to be challenging tasks of utmost importance in synthetic chemistry. The combination of such small molecule activation with subsequent transformations to generate unusual reactivity patterns opens up new prospects for this field of research. Here, we report the reaction of CO 2 and CS 2 with cationic bismuth(iii) amides. CO 2 -uptake gives isolable, but metastable compounds, which upon release of CO 2 undergo CH activation. These transformations could be transferred to the catalytic regime, which formally corresponds to a CO 2 -catalyzed CH activation. The CS 2 -insertion products are thermally stable, but undergo a highly selective reductive elimination under photochemical conditions to give benzothiazolethiones. The low-valent inorganic product of this reaction, Bi(i)OTf, could be trapped, showcasing the first example of light-induced bismuthinidene transfer., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Complexes trans -[PdX 2 L 2 ] (X = Cl and Br), where L is 1-(PR 2 ),2-(CHCH-C(O)Ph)-C 6 F 4 (R = Ph, Cy, and iPr), display phosphorescent emission in the solid state, whereas due to their substantially lower lifetimes, the free ligands exhibit fluorescent behaviour. Alternatively, structurally identical derivatives with halide replaced by CN - or Pd replaced by Pt are non-emissive. DFT calculations explain this diverse behaviour, showing that the hybridization of orbitals of the MX 2 moiety with those of the chalcone fragment of ligands is significant only for the LUMO of the emissive compounds. In other words, in our complexes, only M L M CT processes ( L M = Metal-perturbed Ligand-centered orbital) lead to observable luminescence.

The multinucleating ligand 2,2'-(propane-1,3-diyldiimino)bis[2-(hydroxymethyl)-propane-1,3-diol] (bis-tris propane, H 6 L) is used in the design of a new family of 3d-4f complexes that display an unusual {LnCu 4 } four-blade propeller topology. We report the synthesis, structure and magnetic characterisation of [LnCu 4 (H 4 L) 4 ](Cl) 2 (ClO 4 )·6CH 3 OH, where Ln = Gd (1), Tb (2), Dy (3), La (4). Previously we have used CH 3 COO - and NO 3 - as co-ligands with bis-tris propane, but here the use of Cl - and ClO 4 - leads to coordination of four {Cu(H 4 L)} units around the central Ln ion. A magneto-structural analysis reveals that the geometrical arrangement of the Cu(II) centres defined by the H 4 L 2- ligands controls the magnetic communication between the different metal centres. DFT calculations performed on the isotropic (Gd) and diamagnetic (La) systems 1 and 4 help to unravel the intriguing exchange interactions.

Enantiopure P -stereogenic methylphosphane-boranes ( S P )-P(BH 3 )PhArMe ( ArMe ; Ar = 1-naphthyl (NpMe), and 2-biphenylyl (BiphMe)) have been used to prepare diphosphanes of the type ArPhPCH 2 PR 2 (R = Ph, iPr or t Bu; ArR ). The ligands have been reacted with [Rh(COD) 2 ]BF 4 to furnish the corresponding six monochelated [Rh(COD)( ArR )]BF 4 organometallic compounds (RhArR) or, depending on the reaction conditions, the bis(chelated) coordination compound [Rh( BiphiPr ) 2 ]BF 4 as a mixture of cis and trans isomers. The crystal structure of cis -[Rh( BiphiPr ) 2 ]BF 4 was obtained. The coordination of the BiphR with [RuCl(μ-Cl)(η 6 - p -cymene) 2 ] 2 under different conditions produced cationic chelated complexes of the type [RuCl(η 6 - p -cymene)(κ 2 - BiphR )]PF 6 (RuBiphR) and the neutral monocoordinated complex [RuCl 2 (η 6 - p -cymene)(κ 1 - 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.

A new family of lanthanide compounds has been synthesized using 1,2-bis(diphenylphosphino)ethane dioxide (dppeO 2 ) 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 [Ln III (dppeO 2 ) 1.5 (NO 3 ) 3 (H 2 O) 0.5 ] n (Ln = Ce (1), Sm (2) and Dy (6)) and the one-dimensional structure [Ln(dppeO 2 )(NO 3 ) 3 DMF] 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.

Three azobenzenes CN(C 6 H 4 )-NN-(C 5 H 4 N) (py-iso), CN(C 6 H 4 )-NN-(C 6 H 4 )CN (cyano-iso) and CN(C 6 H 4 )-NN-(C 6 H 4 )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 {Fe II (CN) 5 3- } 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 {Fe II (CN) 5 3- } moieties, which may even produce, in some cases, non-photoswitchable species containing typically photoactive units.

The reaction of Ln(NO 3 ) 2 ·6H 2 O (Ln = Eu, Tb, Dy and Sm) with ( R )-(-)-α-methoxyphenylacetic acid (R-HMPA) and 1,10-phenanthroline (phen) in EtOH/H 2 O 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 Eu 3+ and Tb 3+ ones, whose emission color can be perceived by the naked eye. For the Eu 3+ and Tb 3+ derivatives the quantum yield and the circular polarized luminescence have been measured. For the magnetic allowed transition 5 D 0 → 7 F 1 of the Eu 3+ compound, the anisotropy factor g lum is ±0.013 (+for S-Eu). Also, magnetic properties of all compounds were studied with the Dy 3+ analogue showing slow relaxation of the magnetization under a direct current magnetic field of 1000 Oe.

A family of copper(II)/manganese(II) new clusters with the formulas [Cu II Na I (L2)(MeOH)(ClO 4 )] (1), [CuII2Mn II ( S , S -L3) 2 (MeOH)](ClO 4 ) 2 (2SS), [{Cu II Mn II (L1)(H 2 O) 2 (MeOH)}{Cu II (L1)} 2 ](ClO 4 ) 2 (3), [(μ 1,3 -N 3 ) 2 {Cu II Mn II (L2)(H 2 O)} 2 {Cu II (L2) 2 ](ClO 4 )} 2 (4) and [(μ 1,1 -N 3 ) 2 {Cu II Mn II (L1)(N 3 )} 2 {Cu II Na I (L1)(MeOH)} 2 ](ClO 4 ) 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.

The synthesis and characterization of two dinuclear and five tetranuclear gold(I) complexes bearing the 2,6-bis(diphenylphosphinomethyl)pyridine diphosphane ligand (DPPMPY) are herein reported. The reaction between the dinuclear complexes, DPPMPY(AuCl) 2 (1) or DPPMPY(AuBr) 2 (2), with 1 or 2 equivalents of Ag salts yielded five tetranuclear gold(I) complexes, DPPMPY 2 Au 4 X 2 (3-7), differing in the terminal ancillary ligands (X = Cl, Br, acetonitrile) and the counter ions (SbF 6 - or BF 4 - ). The structures of complexes 1, 2, 3, and 5 were confirmed by single-crystal X-ray diffraction studies. The Au⋯Au distances found in complexes 3 and 5 are in the range of aurophilic interactions and the arrangement of the Au atoms varies from a linear arrangement in complex 3 to a zigzag arrangement in complex 5. The photophysical characterization of the compounds was performed both in solution and in the solid state. Very high emission quantum yields were observed for the acetonitrile complexes 4 and 6 in the solid state. The use of this family of gold(I) complexes as catalysts for lactone synthesis via oxidative heteroarylation of alkenes was investigated and yields up to ca. 65% were obtained. Dicationic halide complexes 3 and 5 showed a slight enhancement of the yield of the catalytic reaction, indicating that there is no influence of the counter ion employed on the reaction outcome. Luminescence techniques have been also used to follow the progress of the catalytic reaction.

The reaction between the 2-(1-(2,6-di(pyrazol-1-yl)-4-methylpyridyl)-4,5-(4,5-bis(propylthio)-tetrathiafulvalenyl)-1 H -benzimidazol-2-yl)-pyridine ligand (L), 1 equivalent of Ln(hfac) 3 ·2H 2 O/Dy(tta) 3 ·2H 2 O (hfac - = 1,1,1,5,5,5-hexafluoroacetylacetonate, tta - = 2-thenoyltrifluoroacetonate) and M(hfac) 2 ·2H 2 O leads to the formation of heteroleptic 3d-4f dinuclear complexes of formula [MLn(hfac) 5 (L)] n (M(II) = Cd, Zn, Co, Mn, Ni and Ln(III) = Dy, Yb, Nd) and [ZnDy(tta) 2 (hfac) 3 (L)]·(CH 2 Cl 2 ). Their X-ray structures reveal that the two coordination sites are occupied by one Ln(III) ion and one M(II) transition metal respectively. The M(II) ions are coordinated to the benzoimidazolylpyridine (bzip) moiety in a N 2 O 4 coordination sphere, while the Ln(III) ions are coordinated to the 2,6-di(pyrazol-1-yl)-4-pyridine (dpp) moiety in a N 3 O 6 surrounding. When Dy(III) ion is used a field-induced Single-Molecule Magnet (SMM) behavior is detected with a magnetic relaxation time slightly dependent to the nature of the vicinal divalent transition metal. On the other hand, when the Yb(III) is used, intense, moderated or quenched 2 F 5/2 → 2 F 7/2 NIR luminescence is observed when the Yb(III) ion is respectively associated with the Zn(II), Mn(II) and Ni(II)/Co(II) ion. The emission intensity can be modulated in function of the metal-to-ligand charge transfer and d-d transition intensities. The replacement of the divalent transition metal by a trivalent lanthanide leads to the formation of heteroleptic 4f-4f' dinuclear complexes of formula [Ln 2- x Ln' x (hfac) 6 (L)]· a (CH 2 Cl 2 )· b (C 6 H 14 ) and [Dy 1.11 Nd 0.89 (tta) 3 (hfac) 3 (L)]. The coordination selectivity is based on the radius. Among the 4f-4f' series, the Dy(III) derivatives displayed such ion in N 2 O 6 eight-coordinated sphere allowing the observation of SMM behavior. The three compounds [Dy 1.21 Nd 0.79 (hfac) 6 (L)]·2(CH 2 Cl 2 )·(C 6 H 14 ), [Yb 1.04 Nd 0.96 (hfac) 6 (L)] and [YbPr(hfac) 6 (L)] displayed respectively Nd(III), modarated Yb(III) and intense Yb(III) NIR emissions.

The synthesis of the gold(I) alkynyl-fluorene compound 2 containing a diphosphane (dppb = 1,4-bisdiphenylphosphanebutane) has been easily achieved by the treatment of the previously synthesized [2-ethynylfluorene-Au] n polymer (1) and the corresponding dppb diphosphane in an adequate 2 : 1 stoichiometry. Compound 2 shows a boat-tweezer conformation that makes it ideal for being used as a host in molecular recognition processes. Different polyaromatic hydrocarbons (PAHs) and polyfluorinated compounds (PFCs) have been used as guests and a stronger interaction has been detected for PAHs, especially for anthracene, in agreement with spectrofluorometric titrations and the calculated values of the association constants, which is confirmed by DFT calculations. Compound 2 has then been immobilized in different organic matrices, in order to enhance room temperature phosphorescence (RTP). This promotes sensing with dual emission and furthermore in the case of the analytes under investigation, phosphorescence is observed in a range of wavelengths that do not coincide with the fluorescence emission of PAHs and PFCs.

The traditional and widespread rationale behind the stability trend of alkyl-substituted carbocations is incomplete. Through state-of-the-art quantum chemical analyses, we quantitatively established a generally overlooked driving force behind the stability of carbocations, namely, that the parent substrates are substantially destabilized by the introduction of substituents, often playing a dominant role in solution. This stems from the repulsion between the substituents and the C-X bond.

The magnetism of transition metal clusters has been for decades a complicated puzzle, with experimental results disagreeing with calculations performed within the density functional theory formalism. In this work, we provide a key to this puzzle by investigating the lowest-energy spin states of cobalt cluster, Co n + ( n ≤ 5), using CASSCF/NEVPT2 calculations with very large active spaces. The geometries as well as the spin configurations adopted by the clusters in their ground-state are known from experiments, making Co n + clusters an ideal model system for theoretical investigation. Here, using the experimentally known geometries determined by far-infrared spectroscopy as inputs, we calculated the lowest-energy spin configurations of the clusters, revealing that the CASSCF/NEVPT2 formalism correctly predicts the preferred electronic configuration of the clusters known experimentally. This is in contrast to the widely used density functional theory, with results that depend on the selected exchange-correlation functional. The reasons for the failure of density functional theory, in opposition to CASSCF/NEVPT2, are discussed, providing a solid framework for investigating other transition metal and transition metal oxide clusters.

The anion SiF 6 2- exerts a strong template effect, driving the exclusive assembly of two different bispyridylpyrazolyl ligands into a triple stranded Fe(II) dinuclear heteroleptic helicate, engendering a new class within the large family of coordination helicates.

Ni(I) compounds are less common than those of either Ni(0) or Ni(II). Recently, a series of Ni(I) tris(2-pyridylmethyl)amine (TPA) complexes were synthetized through the reduction of Ni(II)-TPA complexes and their stabilization was attributed to the formation of H-bonds ( Chem. Commun. , 2021, 57 , 753-756). Because of the growing relevance of Ni(I) complexes in the field of catalysis, we targeted density functional theory simulations to fully characterize the Ni(I) and Ni(II) TPA complexes and understand the role of H-bonding in the stability of Ni(I)-TPA complexes. Our results prove the important contribution of H-bonding in the stability of TPA-Ni(I)-F complexes, which is estimated to increase the Ni(I)-F strength by about 6 to 15 kcal mol -1 .

An asymmetric bis-phenol-β-diketone (H 4 L) has been designed as a ligand programmed to promote the assembly of a molecular arrangement composed of three magnetically exchanged [NiCu] pairs, each exhibiting an S = 1/2 spin. The latter are shown by EPR and magnetometry to be good qubit realizations and non-equivalent within the molecule in the solid state, as required for conditional quantum gates.