•Two TbIII and SmIII clusters with different nuclearity were obtained under identical conditions.•β-diketone ligands present different coordination modes within two clusters.•Their magnetic and luminescent properties were investigated and elucidated in detail.Under the identical reaction conditions, two new TbIII and SmIII-hydroxo clusters with different nuclearity have been prepared and characterized by X-ray crystallography, spectroscopic methods and magnetic measurements. Solid-state structure analyses reveal that the TbIII cluster shows a pentanuclear square pyramidal shape of the composition [Tb5(μ3-OH)4(μ4-OH)(dbm)10]·2H2O (1, dbm– = dibenzoylmethanate) with the dbm ligands presenting two types of coordination modes [η2-and (μ-O)-η2-]. The SmIII species presents a tetranuclear parallelogram structure formulated as [Sm4(μ3-OH)2(dbm)10]·12H2O (2), and three types of coordination modes [η2-, (μ-O)-η2- and (μ-O)2-η2-] for dbm ligands are observed. The measurements of magnetic properties indicate that the direct-current (dc) magnetic behaviors of two clusters mainly result from the thermal depopulation of the Stark sublevels of the TbIII and SmIII ions, respectively. Meanwhile, alternating current (ac) magnetic susceptibility of 1 is also assessed. Investigations on luminescence properties show that 2 displays characteristic emission of the SmIII ion in visible range, while 1 does not exhibit any detectable emission. The interpretations of different emission behaviors for 1 and 2 are also presented in detail.Two new TbIII and SmIII clusters with different nuclearity were obtained under identical reaction conditions. Their luminescent and magnetic properties were investigated and the results were elucidated in detail.

The structures and properties of two mononuclear Dy(III) enantiomeric pairs were dramatically controlled by crystallization temperature; the enantiomeric pair with coordinated chiral N,N′-donor ligands exhibits enhanced single-ion magnetic, ferroelectric and chiroptical properties with respect to the other one with protonated chiral N,N′-donor ligands.

•A chiral silver(I) complex with 1D zigzag chain structure was obtained.•C–H⋯π interactions lead to the formation of a 3D supramolecular framework.•Displaying ferroelectricity, SHG and emission properties.Using a chiral bis-bidentate isomer (–)-2,5-bis(4,5-pinene-2-pyridyl)pyrazine (LR) as bridging ligand to react with AgNO3 under solvothermal conditions, a chiral silver(I) complex formulated as [Ag(LR)·NO3]n (1) was obtained. Single crystal X-ray analysis revealed that 1 crystallizes in the non-centrosymmetric space group C2 with an infinite one-dimensional (1D) zigzag chain structure which is further linked together by C–H⋯π interactions to form a three-dimensional (3D) supramolecular framework. Each four-coordination Ag(I) atom is ligated by four N atoms from two LR ligands forming a distorted tetrahedral geometry. Circular dichroic (CD) spectrum confirmed its chiroptical activity. The measurements of second harmonic generation (SHG) and ferroelectric behavior showed that 1 displays nonlinear optical (NLO) activity and ferroelectricity. Furthermore, the investigation on luminescence property showed that 1 exhibits ligand center emission. All these indicate that 1 presents potential molecular-based multifunctional materials.A new chiral silver(I) complex with tree-dimensional (3D) supramolecular structure was synthesized by using designed chiral bis-bidentate bridging ligand. It possesses chiroptical activity along with SHG, ferroelectric and emission properties, being potentially molecule-based multifunctional materials.

•A pair of NdIII enantiomers were prepared based on the enantiopure bis-bidentate N-donor ligands.•Mirror-symmetrical CD spectra confirmed their chiroptical activities and enantiomeric nature.•Displaying characteristic near-infrared (NIR) emissions of NdIII ions with notable lifetime value.Based on enantiopure bis-bidentate N-donor ligands (−)/(+)-2,5-bis(4,5-pinene- 2-pyridyl)pyrazine (LR/LS), a new pair of NdIII enantiomers with the formula Nd(dbm)3LR/S·2H2O (R-1 and S-1 being the isomers containing the LR and LS ligands, respectively, and dbm = dibenzoylmethanate) have been isolated and characterized by X-ray crystallography and spectroscopic methods. Notably, unlike our previously reported homodinuclear EuIII and DyIII complexes based on the identical ligands (LR and LS), the dinuclear NdIII congener have not been obtained by controlling the ligand-to-metal ratio as expected, the reason of which was elucidated in this work. The crystal structure analyses of R-1 and S-1 reveal that they are mononuclear NdIII complexes and crystallize in chiral space group P212121 of the orthorhombic system. Circular dichroic (CD) spectra confirmed their chiroptical activities and enantiomeric nature. The photoluminescence investigations showed that they display characteristic near-infrared (NIR) emissions of the NdIII ions with notable emitting lifetime value.A pair of NdIII enantiomers were prepared based on the enantiopure bis-bidentate N-donor ligands. Mirror-symmetrical CD spectra confirmed their chiroptical activities and enantiomeric nature. They display characteristic NIR emissions of NdIII ions with notable lifetime values.

Using the enantiopure bis-bidentate ligands (−)/(+)-2,5-bis(4,5-pinene-2-pyridyl)pyrazine (LR/LS), two mono- and dinuclear SmIII enantiomeric pairs with the formulae [Sm(dbm)3LR/S]·C2H6CO·H2O (R-1 and S-1 being the isomers containing the LR and LS ligands, respectively, and dbm = dibenzoylmethanate) and [Sm2(dbm)6LR/S]·2H2O (R-2 and S-2 being the isomers containing the LR and LS ligands, respectively) have been synthesized and characterized by X-ray crystallography and spectroscopic technologies. The nuclearity of the complexes isolated depends on the ratio of the reactants. Circular dichroic (CD) spectra confirmed their chiroptical activities and enantiomeric natures. Measurement of the luminescence properties revealed that both the mono- and dinuclear SmIII complexes display the characteristic deep-red emissions of SmIII ions in the solid state. Notably, in contrast to the previously reported dinuclear SmIII complex based on a bis-β-diketonate ligand, whose emission intensity is much larger than that of the mononuclear analog, the intensity of the emission signal for the mononuclear complex R-1 is more than ten times larger than that of the dinuclear species R-2. The reason for this phenomenon is elucidated in this work. Thus, our research results demonstrate that the Sm nuclearity has a considerable effect on the photophysical properties of SmIII mono-β-diketonate complexes, which is contrary to the observation in SmIII bis-β-diketonate complexes.Using enantiopure bis-bidentate ligands, two mono- and dinuclear SmIII enantiomeric pairs have been synthesized, depending on the ratio of the reactants. The photophysical properties of the mononuclear SmIII enantiomers are superior to those of the dinuclear SmIII analogs, demonstrating that the Sm nuclearity has a considerable effect on their photophysical properties.

The reaction of enantiomeric bis-bidentate bridging ligands (+)/(−)-2,5-bis(4,5-pinene-2-pyridyl)pyrazine (LS/LR) with [Re(CO)5Cl] yielded a pair of dinuclear Re(I) enantiomers formulated as [Re2(LS/LR)(CO)6Cl2]·4CH2Cl2 (R-1 and S-1, the isomers containing the respective LR and LS ligands). They were characterized by elemental analyses, IR spectra and X-ray crystallography. Circular dichroism spectra verified their chiroptical activities and enantiomeric nature. The measurements of second harmonic generation (SHG) and ferroelectric properties showed that R-1 displays a nonlinear optical (NLO) activity and ferroelectricity with a remnant polarization (Pr) of 1.6 μC cm−2 under an applied field of 7.3 kV cm−1 at room temperature. R-1 and S-1 represent the first example of polynuclear Re(I) complexes with ferroelectric properties. Notably, the Pr value is much larger than that of the reported mononuclear chiral Re(I) analogue. In particular, unlike mononuclear Re(I) complexes of the type [Re(CO)3(N^N)(X)] (N^N = diimine and X = halide), which usually exhibit an intense emission in the visible range, R-1 and S-1 do not show any detectable emission at any temperature range and the reason for the nonluminescence of R-1 and S-1 was further elucidated in this work. Moreover, our research results also elucidated that Re nuclearity has a great influence on not only the emitting properties but also on ferroelectric behavior.

Reaction of the chiral ligand (−)-4,5-pinenepyridyl-2-pyrazine (L) with Ln(hfac)3·2H2O precursors [hfac− = 1,1,1,5,5,5-hexafluoroacetylacetonate, Ln = Sm3+ (1), Eu3+ (2), Tb3+ (3) and Dy3+ (4)] in methanol solution led to the formation of four noncentrosymmetric lanthanide complexes with the general formula [Ln(hfac)3L]n·H2O. The single-crystal X-ray diffraction analyses revealed that they are isostructural and take a one-dimensional (1D) chain structure based on the Ln(hfac)3L repeating units, in which the nine-coordinate Ln3+ ions reside in a tricapped trigonal prism (TTP) environment never reported in previous 1D chain lanthanide complexes. The investigations of their photophysical properties showed that complexes 1, 2 and 3 exhibit characteristic emissions of Sm3+, Eu3+ and Tb3+ ions with respective luminescent lifetime values of 0.065, 1.066 and 0.129 ms, while complex 4 does not display any emission. The different luminescent intensities and lifetimes among them were further discussed in detail. Moreover, the magnetic properties of complexes 1–4 were assessed with a special emphasis on the Dy3+ complex 4. Alternating-current (ac) magnetic susceptibility measurements indicated that field-induced two-step slow magnetic relaxation processes were observed in 4, indicating the single-molecule magnet (SMM) behavior of 4. In addition, the noncentrosymmetric complexes 1–4 crystallizing in the same polar point group (Cs) exhibit both ferroelectric and nonlinear optical properties at room temperature. All these features make them multifunctional crystalline molecule materials.

The reactions of enantiopure chiral ligands (+)/(−)-4,5-pinenepyridyl-2-pyrazine (LS/LR) with CuCl2·2H2O in CH3OH/CH2Cl2 solution led to the formations of one-dimensional homochiral enantiomeric pairs with the formula [Cu(LR/S)Cl2]n·2H2O (R-1 and S-1, the isomers containing the LR and LS ligands, respectively). The circular dichroism (CD) spectra verified their chiroptical activities and enantiomeric natures. Their structures have been determined by X-ray single-crystal analyses, showing stairway-like and mirror-symmetric features, which represent the first examples of homochiral metal complexes with stairway-like structures. The ferroelectric property measurement indicated that R-1 exhibits ferroelectricity with the remnant polarization (Pr) value of 0.02 μC cm−2 under an applied electric field of 6.1 kV cm−1 at room temperature. The magnetic investigation of R-1 showed a weak intrachain antiferromagnetic coupling between Cu(II)–Cu(II) ions mediated by pyrazine, which can be interpreted by a spin-polarization mechanism. All these results suggested that R-1 and S-1 are potential multifunctional molecule-based materials combining optical activity, ferroelectricity and magnetism within one molecule.

Highlights•Three Nd3+, Er3+ and Yb3+-containing enantiomeric pairs confirmed by X-ray single-crystal analyses and CD spectra.•Displaying characteristic near-infrared (NIR) emissions of respective Nd3+, Er3+ and Yb3+ ions with notable lifetime values.•Representing the first example of chiral lanthanide β-diketonate complexes with NIR luminescent property.Three lanthanide-based enantiomeric pairs formulated as Ln(dbm)3LR/S (Ln = Nd3+ (R-1 and S-1), Er3+ (R-2 and S-2) and Yb3+ (R-3 and S-3), R- and S-configuration complexes containing the LR and LS ligands, respectively, and dbm = dibenzoylmethanate) have been obtained successfully upon the reaction of corresponding lanthanide precursors Ln(dbm)3·H2O with enantiopure chiral ligands (−)/(+)-4,5-pinene bipyridine (LR/S), respectively. Their structures were characterized by X-ray single-crystal analyses, elementary analyses and IR spectra. The circular dichroic (CD) spectra verified their chiroptical activities and enantiomeric natures. The photoluminescence investigations demonstrated that they display characteristic near-infrared (NIR) emissions of corresponding Nd3+, Er3+ and Yb3+ ions with notable lifetime values, representing the first example of chiral lanthanide β-diketonate complexes with NIR luminescent property.Graphical abstractThree Nd3+, Er3+ and Yb3+-containing enantiomeric pairs were prepared based on the enantiopure N-donor ligands. They display characteristic NIR luminescence of the corresponding lanthanide ions, representing the first example of chiral lanthanide β-diketonate complexes showing NIR luminescent property.

A rhenium(I) complex ReLR,R(CO)3Cl (1) based on a chiral ligand, LR,R = (−)-4,5-pinene-2,2′-bipyridine [(6R)-5,6,7,8-tetrohedro-7,7-dimethyl-3-(2-pyridinyl)-6,8-methanoisoquinoline], was synthesized and characterized. The emission spectrum of 1 shows efficient dπ(Re) → π* (diimine) (MLCT) phosphorescence with a photoluminescence quantum efficiency of 0.035. The excited state lifetimes of Re(I) complex, measured in CH2Cl2 solution (1.82 μs) and solid state (2.15 μs) at room temperature, support the hypothesis of the MLCT character of the emitting state. Single crystal X-ray diffraction analyses show that complex 1 crystallizes in the chiral space group P21 of monoclinic system. The P–E hysteresis loop indicates its obvious ferroelectricity with the remnant polarization (Pr) value of 0.17 μC/cm2 at an applied field of 4.8 kV/cm. To the best of our knowledge, complex 1 represents the first rhenium-based complex reported with ferroelectricity.A new chiral rhenium(I) complex was synthesized and structurally characterized, which shows photoluminescent and ferroelectric properties and represents the first example of rhenium-based complex with ferroelectricity.Highlights► A new chiral rhenium(I) complex with crystal structure characterization ► Displaying photoluminescent and ferroelectric properties. ► Representing the first rhenium-based example with ferroelectricity

Using the enantiomeric bis-bidentate bridging ligands (+)/(−)-2,5-bis(4,5-pinene-2-pyridyl)pyrazine (LS/LR) and depending on the ratio control of reactants, two mono- and dinuclear Eu(III)-based enantiomeric pairs with the formulae Eu(dbm)3LR/S·2H2O (LR in R-1, LS in S-1 and dbm = dibenzoylmethanato) and Eu2(dbm)6LR/S·H2O (LR in R-2 and LS in S-2) have been stereoselectively synthesized and structurally characterized. The circular dichroic (CD) spectra confirmed their chiroptical activities and enantiomeric natures. The homochiral dinuclear species represents the first example of a polynuclear lanthanide β-diketonate complexes with circular dichroic and crystallographic evidences. The photoluminescent properties studies revealed that both mono- and dinuclear Eu(III) complexes exhibited the characteristic red emissions of Eu(III) ions in the solid state (at 77 K and 300 K) and CH2Cl2 solution. Notably, the photophysical properties of the mononuclear enantiomers were superior to the dinuclear species. Interestingly, R-2 displayed a ferroelectric property at room temperature, which was not observed for R-1 due to the lack of crystalline polarity. R/S-2 are the first examples of homochiral polynuclear lanthanide complexes with luminescence and ferroelectric properties, being potential multifunctional materials.

Two chiral tetradecanuclear hydroxo-lanthanide clusters of composition Ln14(µ4-OH)2(µ3-OH)16(µ-η2-acac)8(η2-acac)16·6H2O, where Ln = Dy 1, Tb 2 and acac = acetylacetonato, have been prepared and characterized by X-ray crystallographic, magnetic and spectroscopic methods. They crystallize in chiral monoclinic space group C2, which is exceptionally rare in hydroxo-lanthanide clusters, and present luminescent and magnetic properties.

Two new acylpyrazolonate-based lanthanide complexes of formula [Ln(pmap)3(H2O)2]·CH3COOC2H5 (Ln = Tb 1, Eu 2 and pmap = 1-phenyl-3-methyl-4-acetyl-5-pyrazolonate) have been prepared and characterized by X-ray single crystal determination and spectroscopic methods. The crystal structure analysis reveals that 1 and 2 are isostructural and crystallize in the triclinic space group P1¯ with two independent, but structurally similar molecules in the structural unit, which are exceptionally rare in acylpyrazolonate-based mononuclear lanthanide complexes. In CH3CN solution, the photoluminescence investigation demonstrates that 1 displays intensely green emission of Tb(III)-centered, while Eu(III)-complex does not emit characteristically red luminescence. The results are elucidated in terms of the energy gap ΔE(3ππ*–5D4 or 5D0) between Hpmap ligand and resonance levels of Tb(III) or Eu(III) ion.Graphical abstractHighlights► There are two crystallographically independent molecules with different geometries in Tb(III) and Eu(III) structural unit, respectively. ► Acylpyrazolonate-based Tb(III) complex displays intensely green luminescence both in solid state and in solution. ► Hpmap is a good sensitizer for Tb(III) emitting.

As a result of the reaction between Dy(dbm)3·2H2O and chiral ligands LS,S(+)-4,5-pinene bipyridine or LR,R(−)-4,5-pinene bipyridine, a novel DyIII-based enantiomeric pair, Dy(dbm)3LS,S and Dy(dbm)3LR,R, has been obtained and characterized by X-ray single crystal determination and spectroscopic methods. The crystal structure analysis of 1 and 2 reveals that they crystallize in chiral space group P21 of monoclinic system. The central DyIII ion is eight-coordinated with six oxygen atoms of three β-diketonate anions and two nitrogen atoms of chiral pinene bipyridine, forming a coordination polyhedron best described as the distorted square antiprism. The CD spectra reflect that complexes 1 and 2 are enantiomers. Thermogravimetric analysis results indicate that 1 and 2 are thermally stable up to 249 °C.

Novel Sm-based enantiomeric pair, generally formulated Sm(DBM)3L (LR,R in 1, LS,S in 2, DBM = dibenzoylmethanate) have been successfully prepared via the reaction of Sm(DBM)3·2H2O with chiral ligands LR,R (−)-4,5-pinene bipyridine and LS,S (+)-4,5-pinene bipyridine (Scheme 1), respectively. The crystal structure analysis of 1 and 2 reveal that they crystallize in chiral space group P21 of monoclinic system. The central Sm(III) ion is octacoordinate with six β-diketonate oxygen atoms and two chiral pinene bipyridine nitrogen atoms, forming a coordination polyhedron best described as the distorted square antiprism (SA). The CD spectra (Fig. S1) further confirm that 1 and 2 are enantiomers. The photoluminescence investigations of 1 and 2 demonstrate that they display deep-red luminescence characteristic of the Sm3+.Novel Sm-based enantiomeric pair with chiral ligand have been initially synthesized and characterized by crystal structure analysis and spectroscopic methods. They are isostructural, while octacoordinate Sm(III) is situated in a distorted square antiprism (SA) geometrical environment. The investigations on photoluminescence properties reveal that they display deep-red luminescence characteristic of the Sm3+.

The structures and properties of two mononuclear Dy(III) enantiomeric pairs were dramatically controlled by crystallization temperature; the enantiomeric pair with coordinated chiral N,N′-donor ligands exhibits enhanced single-ion magnetic, ferroelectric and chiroptical properties with respect to the other one with protonated chiral N,N′-donor ligands.

Using the enantiomeric bis-bidentate bridging ligands (+)/(−)-2,5-bis(4,5-pinene-2-pyridyl)pyrazine (LS/LR) and depending on the ratio control of reactants, two mono- and dinuclear Eu(III)-based enantiomeric pairs with the formulae Eu(dbm)3LR/S·2H2O (LR in R-1, LS in S-1 and dbm = dibenzoylmethanato) and Eu2(dbm)6LR/S·H2O (LR in R-2 and LS in S-2) have been stereoselectively synthesized and structurally characterized. The circular dichroic (CD) spectra confirmed their chiroptical activities and enantiomeric natures. The homochiral dinuclear species represents the first example of a polynuclear lanthanide β-diketonate complexes with circular dichroic and crystallographic evidences. The photoluminescent properties studies revealed that both mono- and dinuclear Eu(III) complexes exhibited the characteristic red emissions of Eu(III) ions in the solid state (at 77 K and 300 K) and CH2Cl2 solution. Notably, the photophysical properties of the mononuclear enantiomers were superior to the dinuclear species. Interestingly, R-2 displayed a ferroelectric property at room temperature, which was not observed for R-1 due to the lack of crystalline polarity. R/S-2 are the first examples of homochiral polynuclear lanthanide complexes with luminescence and ferroelectric properties, being potential multifunctional materials.

The reactions of enantiopure chiral ligands (+)/(−)-4,5-pinenepyridyl-2-pyrazine (LS/LR) with CuCl2·2H2O in CH3OH/CH2Cl2 solution led to the formations of one-dimensional homochiral enantiomeric pairs with the formula [Cu(LR/S)Cl2]n·2H2O (R-1 and S-1, the isomers containing the LR and LS ligands, respectively). The circular dichroism (CD) spectra verified their chiroptical activities and enantiomeric natures. Their structures have been determined by X-ray single-crystal analyses, showing stairway-like and mirror-symmetric features, which represent the first examples of homochiral metal complexes with stairway-like structures. The ferroelectric property measurement indicated that R-1 exhibits ferroelectricity with the remnant polarization (Pr) value of 0.02 μC cm−2 under an applied electric field of 6.1 kV cm−1 at room temperature. The magnetic investigation of R-1 showed a weak intrachain antiferromagnetic coupling between Cu(II)–Cu(II) ions mediated by pyrazine, which can be interpreted by a spin-polarization mechanism. All these results suggested that R-1 and S-1 are potential multifunctional molecule-based materials combining optical activity, ferroelectricity and magnetism within one molecule.

Reaction of the chiral ligand (−)-4,5-pinenepyridyl-2-pyrazine (L) with Ln(hfac)3·2H2O precursors [hfac− = 1,1,1,5,5,5-hexafluoroacetylacetonate, Ln = Sm3+ (1), Eu3+ (2), Tb3+ (3) and Dy3+ (4)] in methanol solution led to the formation of four noncentrosymmetric lanthanide complexes with the general formula [Ln(hfac)3L]n·H2O. The single-crystal X-ray diffraction analyses revealed that they are isostructural and take a one-dimensional (1D) chain structure based on the Ln(hfac)3L repeating units, in which the nine-coordinate Ln3+ ions reside in a tricapped trigonal prism (TTP) environment never reported in previous 1D chain lanthanide complexes. The investigations of their photophysical properties showed that complexes 1, 2 and 3 exhibit characteristic emissions of Sm3+, Eu3+ and Tb3+ ions with respective luminescent lifetime values of 0.065, 1.066 and 0.129 ms, while complex 4 does not display any emission. The different luminescent intensities and lifetimes among them were further discussed in detail. Moreover, the magnetic properties of complexes 1–4 were assessed with a special emphasis on the Dy3+ complex 4. Alternating-current (ac) magnetic susceptibility measurements indicated that field-induced two-step slow magnetic relaxation processes were observed in 4, indicating the single-molecule magnet (SMM) behavior of 4. In addition, the noncentrosymmetric complexes 1–4 crystallizing in the same polar point group (Cs) exhibit both ferroelectric and nonlinear optical properties at room temperature. All these features make them multifunctional crystalline molecule materials.

Two second-order nonlinear optically (NLO)-active dinuclear and square Cu(II) enantiomeric pairs were obtained via the self-assemblies of enantiopure linear bis-bidentate ligands with different copper(II) salts under the identical reaction conditions. Their magnetic properties are switched from antiferromagnetic to ferromagnetic coupling.

The reaction of enantiomeric bis-bidentate bridging ligands (+)/(−)-2,5-bis(4,5-pinene-2-pyridyl)pyrazine (LS/LR) with [Re(CO)5Cl] yielded a pair of dinuclear Re(I) enantiomers formulated as [Re2(LS/LR)(CO)6Cl2]·4CH2Cl2 (R-1 and S-1, the isomers containing the respective LR and LS ligands). They were characterized by elemental analyses, IR spectra and X-ray crystallography. Circular dichroism spectra verified their chiroptical activities and enantiomeric nature. The measurements of second harmonic generation (SHG) and ferroelectric properties showed that R-1 displays a nonlinear optical (NLO) activity and ferroelectricity with a remnant polarization (Pr) of 1.6 μC cm−2 under an applied field of 7.3 kV cm−1 at room temperature. R-1 and S-1 represent the first example of polynuclear Re(I) complexes with ferroelectric properties. Notably, the Pr value is much larger than that of the reported mononuclear chiral Re(I) analogue. In particular, unlike mononuclear Re(I) complexes of the type [Re(CO)3(N^N)(X)] (N^N = diimine and X = halide), which usually exhibit an intense emission in the visible range, R-1 and S-1 do not show any detectable emission at any temperature range and the reason for the nonluminescence of R-1 and S-1 was further elucidated in this work. Moreover, our research results also elucidated that Re nuclearity has a great influence on not only the emitting properties but also on ferroelectric behavior.