This study is focused on determining the refractive index as a crucial parameter for evaluating the intrinsic quantum yield and the ligand sensitisation efficiency in solid-state trivalent lanthanide coordination compounds. For this, eight trivalent europium complexes with phenyl-terpyridine ([EuX3(ptpy)(L)], X = Cl– or NO3–, ptpy = 4'‑phenyl‑2,2':6',2''‑terpyridine, L = H2O or other molecules) were examined. Their refractive indices were determined using the Becke lines test by immersing transparent material in a series of media with known refractive indices. Using the set of media presented here, determining crystalline materials' refractive indices from 1.41 to 1.73 with a step of 0.01 is possible. Assessment of the refractive indices of the complexes mentioned above allowed a comprehensive analysis of their photophysical properties in the solid state. Moreover, this method can be extrapolated for other solid-state materials, offering valuable insights in the broader field of photophysics. In addition to photoluminescence investigations, the compounds presented were characterised by single-crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), Hirschfeld surface area analysis, UV‑Vis reflectance spectroscopy, hydrolysis sensitivity analysis, and simultaneous thermogravimetry and differential thermal analysis coupled with mass-spectrometry (STA-MS).

1,10-Phenanthroline d- or f-metal complexes can be utilised in biomedical applications such as imaging or therapeutics. Herein, we designed bimetallic d-block metal-phenanthroline f-block metal-1,4,7,10-tetraazacyclododecane-1,4,7,1,0-tetraacetic acid (DOTA) conjugates as theranostic agents to simultaneously achieve both of these applications. Luminescence studies show the 1,10-phenanthroline-Eu(III)-DOTA complexes displayed an off/on/off pH-dependent switch, demonstrating their potential as pH-responsive lanthanide luminescence probes. Relaxometry studies showed that the 1,10-phenanthroline-Gd(III)-DOTA complexes present a r1 of 5.15 ± 0.05 mM-1 s-1 and could thus be used as magnetic resonance (MR) contrast agents. Complexation of Pt(II) by the 1,10-phenanthroline moiety resulted in quenching of the Eu(III) luminescence, but an enhancement of the Gd(III) relaxivity (r1 = 7.53 ± 0.69 mM-1 s-1). Cell viability studies of the d-f hybrids in a cancer cell line showed the potential of these complexes as anticancer agents, as the IC50 for the Pt(II)/Gd(III) complex (IC50 = 24.9 μM) was lower than that of cisplatin (IC50 = 31.6 μM). As such, Pt(II)-1,10-phenanthroline-Gd(III)-DOTA complexes are promising theranostic agents for cancer therapy.

The reactivity of complexes [Fe2(µ-S2)(CO)4L2] (L = CO (1), PPh3 (2)), with lithium alkynylide reagents generated in situ, was investigated. The behavior of the S2-bridge in these compounds depends on the substitution at the diiron core. The reaction with the hexacarbonyl derivative 1 leads to the formation of the 1,2-dithiolene bridged complex [Fe2(µ-SCH=C(R)S)(CO)6] (3R) while the molecule [Fe2(µ-SH)(µ-SC≡CR)(CO)4(PPh3)2] (5R), with an open butterfly structure, is isolated when reacting the disubstituted derivative 2. The disubstituted dithiolene complex [Fe2(µ-SCH=C(Ph)S)(CO)4(PPh3)2] (4Ph) can only be obtained by substitution of carbonyls with PPh3 in 3R. In the presence of piperidine, 5R isomerizes into the 1,1’-dithiolene bridged derivative 6Ph. The novel compounds 4-6 were synthesized and characterized by IR and NMR spectroscopies. X-ray crystallographic studies of the dithiolene complexes 3Ph-4Ph allowed their structural analysis.

The magnetic properties of the trinuclear complexes M₂UL (M^II=Co, Ni, Cu), exhibiting the 3d–5 f–3d core configuration, have been computationally investigated using the relativistic DFT/B3LYP/BS approach. The calculated coupling J _M-U constants agree with the observed antiferromagnetic of the Co₂UL and Ni₂UL complexes vs. ferromagnetic Cu₂UL one.

Abstract

The magnetic properties of the trinuclear Schiff base complexes M₂UL⁷ (M^II=Co, Ni, Cu; L⁷=N,N’-bis(3-hydroxysalicylidene)-2,2-dimethyl-1,3-propanediamine), exhibiting the [M(μ-O)₂]₂U core structure (3d-5 f-3d subsystem), have been investigated theoretically using scalar relativistic ZORA/DFT computations combined with the broken symmetry (BS) approach. The calculated coupling constants J _MU between the adjacent M1−U and M2−U agree with the observed ferromagnetic (Ferro) character observed in the case of the Cu₂UL⁷ complex, the antiferromagnetic (AF) character of the Ni₂UL⁷ one is consistent with the experimentally observed AF behaviour for Co₂UL⁷. The structural parameters, in particular the M−U distances and the M−O_b−U angles, as well as the electronic factors driving the superexchange couplings are discussed. The bond orders and the magnetic molecular orbital analyses reveal that the U(5 f) covalent contribution to the bonding within the M−O−U coordination is more important in the Co₂UL⁷ and Ni₂UL⁷ complexes than in the Cu₂UL⁷ congener, thus favouring AF coupling between the transition metal and the uranium magnetic centers, in the first complexes. The analyses are supported by the study of the mixed ZnMUL⁷ and M₂ThL⁷ systems, where the Co^II (3d⁷) and Ni^II (3d⁸) paramagnetic ions are replaced by the diamagnetic Zn^II(3d¹⁰) one, whereas in the second complex, the U^IV(5f²) paramagnetic center is replaced by the diamagnetic Th^IV(5f⁰) one. The Natural Populations Analyses confirm the crucial role of spin delocalization that is at work in favour of the AF vs. Ferro magnetic character of the M−U−M (M=Ni, Co) and Cu−U−Cu coordination, respectively.

Collision-induced dissociation (CID) of the mass-selected cation [(bipy)Pt(CH3)2(CH2SCH3)]+ in an ion-trap mass-spectrometer results in the losses of the neutrals ethane, ethene, dimethyl sulfide, methane, ethyl methyl sulfide, and propane. The generation of the first four neutrals is also observed, when the isolated, dimeric complex [(bipy)Pt(CH3)2(CH2SCH3)]2[SbF6]2 is heated in the condensed phase. While the product distribution is very similar regardless of whether the complex is heated in the solid state or in solution, ethane loss, i.e. the quite rare event of an sp3-sp3 C–C reductive elimination from a platinum(IV) complex, dominates in the gas-phase experiment. However, when the counter anion [SbF6]- is exchanged by the more weakly coordinating anion [BAr4F]-, the amounts of ethane and ethene are increased also in the condensed phase. These sum of observations indicates the similarities of the fragmentation of [(bipy)Pt(CH3)2(CH2SCH3)]+ in both phases. Thus, a correlation of processes in both environments is possible for selected systems (and particularly for unimolecular processes), but the choice of the proper conditions is crucial for a meaningful comparison.

ZnIn2S4 has been regarded as a promising photoanode material for photoelectrochemical (PEC) water splitting. However, its severe charge recombination and low carrier transport efficiency limit practical applications in PEC water separation. A novel ZnIn2S4/Au/PB photoanode was prepared by in situ photodeposition and electrodeposition. The photocurrent density of the ternary photoanode reached 0.42 mA/cm2 at 1.23 VRHE, which is 6 times higher than that of pure ZnIn2S4. The introduction of Au nanoparticles remarkably improved the efficiency of carrier transport and separation. Additionally, the application of PB onto ZnIn2S4 resulted in an extended spectrum of light absorption. The incident photon-to-current efficiency (IPCE) value recorded was 24.6% at 350 nm. This improvement can be attributed to the formation of a Z-type heterojunction.

Two five-coordinate mononuclear DyIII single-molecule magnets [(TrapenTMS)Dy(L)] (Trapen = tris(2-aminobenzyl) amine; TMS = SiMe3; L = OPMe31, OPEt32) have been synthesized by the reaction of [(TrapenTMS)Dy(THF)] and OPMe3, OPEt3, respectively. The molecular structures of 1 and 2 were fully established by single crystal X-ray diffraction. The centre DyIII ions of both complexes exhibit distorted triangular bipyramid geometries, varying with different neutral ligands L on the apex. The TrapenTMS ligand forms the pyramid base of the trigonal bipyramid. Subtle structural modifications of the axial O-ligand terminal substituent result in different dynamic magnetic behaviors.Magnetic data analysis reveals that 1 and 2 exhibit the characteristic behavior of SMM without a dc field, accompanying an unambiguous quantum tunneling of the magnetization. Field-induced slow magnetic relaxation was observed for 1 and 2 under an applied bias dc field of 1000 Oe, the relaxation energy barriers are 107 K and 88 K for 1 and 2, respectively. We have investigated the differences in magnetism and magnetic anisotropy between the two complexes by ab initio calculations.

The reaction mechanism for the formation of the pseudo-silaazatriene 1 by the reaction of 1 equivalent of bis-silylene with 3 equivalents of azide Me3SiN3 has been explored at M06/def2-TZVPP//BP86-D3(BJ)/def2-TZVPP level of theory. The reaction mechanism is guided by the high Lewis basicity of the silicon lone pair and the high Lewis acidic character of Si-N bonds, as well as by the high tendency to eliminate N2 from Me3SiN3. The first step of the reaction is the formation of [3+1] cycloaddition product (I1) by the synergetic interactions of the lone pair on the silylene silicon with the π* molecular orbital of Me3SiN3 which is majorly localized on the terminal nitrogen atom, and the donation of the σ-type lone pair on the nitrogen atom connected to the SiMe3 group with the Si-N σ* orbital on silylene. The elimination of N2 from I1 results in the formation of pseudo-silaimine intermediate I2 having a dicoordinated, monovalent nitrogen atom. The Si-Si bond cleavage of I2 results in intermediate I3, which is susceptible to [3+1] cycloaddition reaction with two molecules of Me3SiN3 in a stepwise manner results in I7 having two silaimine and one silaamine moieties. Further 1,3-silyl migration results in pseudo-silaazatriene 1.

Heat-storage materials are important for energy saving to protect the environment. Here, we show a long-term heat-storage material based on zirconium-substituted lambda-trititanium pentoxide (λ-ZrxTi3-xO5, 0 < x ≤ 0.06). λ-ZrxTi3-xO5 exhibits a phase transition to zirconium-substituted beta-trititanium pentoxide (β-ZrxTi3-xO5) upon application of pressure. The transition pressures were 600 MPa (x = 0.04) and about 1 GPa (x = 0.06). When the pressure-produced β-phase is heated, the β-phase transforms into λ-phase. The phase transition temperatures (i.e., heat-storage temperatures) were 185 °C (458 K) and 183 °C (453 K) for x = 0.04 and 0.06, respectively. These heat-storage temperatures are suitable for the reuse of low-temperature industrial waste heat, which are considered to be a difficult temperature region to be efficiently collected and reused. The present pressure-sensitive heat-storage ceramic, which can store the latent heat energy for a prolonged period, is effective for the sustainable reuse of heat energy that are wasted in power plants and industrial factories.

In this paper we report the microwave assisted synthesis and characterization of a family of Na-Ln coordination polymers (CPs) of formula [NaDy2(MeCOO)2(SALOH)5(chpH)2] (1Ln, Ln = Eu, Gd, Tb, Dy, Ho, Y). The Na+ cations isolate Ln2 units in a one-dimensional polymer. By changing the lanthanoid ions, we attain Single Molecule Magnet properties (1Dy), luminescent properties (1Eu, 1Tb, 1Ho), a diamagnetic material (1Y) and a material that presents magnetocaloric effect (1Gd).