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Optically active functional noncentrosymmetric architectures might be achieved through the combination of molecules with inscribed optical responses and species of dedicated tectonic character. Herein, we present the new series of noncentrosymmetric cocrystal salt solvates (PPh 4 ) 3 [M(CN) 6 ](L) n · m solv (M = Cr(III), Fe(III), Co(III); L = polyresorcinol coformers, multiple hydrogen bond donors: 3,3',5,5'-tetrahydroxy-1,19-biphenyl, DiR, n = 2, or 5'-(3,5-dihydroxyphenyl)-3,3″,5,5″-tetrahydroxy-1,19:3',1″-terphenyl, TriRB, n = 1) denoted as MDiR and MTriRB , respectively. The hydrogen-bonded subnetworks {[M(CN) 6 ] 3- ;L n } ∞ of dmp , neb , or dia topology are formed through structural matching between building blocks within supramolecular cis -bis(chelate)-like {[M(CN) 6 ] 3- ;( H 2 L) 2 ( H L) 2 } or tris(chelate)-like {[M(CN) 6 ] 3- ;( H 2 L) 3 } fragments. The quantum-chemical analysis demonstrates the mixed electrostatic and covalent character of these interactions, with their strength clearly enhanced due to the negative charge of the hydrogen bond acceptor metal complex. The corresponding interaction energy is also dependent on the geometry of the contact and size matching of its components, rotational degree of freedom and extent of the π-electron system of the coformer, and overall fit to the molecular surroundings. Symmetry of the crystal lattices is correlated with the local symmetry of coformers and {complex;(coformer) n } hydrogen-bonded motifs characterized by the absence of the inversion center and mirror plane. All compounds reveal second-harmonic generation activity and photoluminescence diversified by individual UV-vis spectral characteristics of the components, and interesting low-frequency Raman scattering spectra within the subterahertz spectroscopic domain. Vibrational (infrared/Raman), UV-vis electronic absorption (experimental and calculated), and 57 Fe Mössbauer spectra together with electrospray ionization mass spectrometry (ESI-MS) data are provided for the complete description of our systems.

Research on isomers is highly desirable due to their prospective role in better understanding of physicochemical properties of similar systems and further development of multifunctional molecular materials. Iron(II) and tetra(thiocyanato)mercury(II) ions self-assembled in the presence of 2-acetylpyridine (2-acpy) excess to form two {[Fe(2-acpy)][Hg(μ-SCN) 4 ]} n isomers: two-dimensional (2D) centrosymmetric layers with folded ring structural motifs ( 1 ) and three-dimensional (3D) chiral networks with right- or left-handed {···Fe-NCS-Hg-SCN···} ∞ helixes ( 2 ). New methods of designing and synthesizing functional thiocyanate-bridged materials have been proposed. In addition, the similarity between 1 and 2 allowed for the description of subtle changes in IR and UV-visible spectra. Moreover, 2 shows spontaneous resolution, and it crystallizes in the noncentrosymmetric space group P 2 1 , leading to the occurrence of nonlinear optical activity in circular dichroism studies and second harmonic generation (SHG). At room temperature, the SH susceptibility for powder sample 2 reached 6.0 × 10 -11 esu. Ab initio calculations indicated the electric polarization vector and the crystallographic twofold screw axis pass through the aromatic ring. Magnetic studies for 1 and 2 revealed high-spin iron(II) with zero-field splitting at low temperatures. Analysis of magnetic data gave | D| = 37.45 cm -1 , | E / D | = 5.59 cm -1 , and ⟨ g ⟩ = 2.15 for 1 , | D| = 36.78 cm - 1 , | E / D | = 4.92 cm -1 , and ⟨ g ⟩ = 2.18 for 2 , and information about the orientation of magnetic anisotropy vectors for both compounds.

Coordination compounds built of trivalent lanthanide ions have been demonstrated as promising solid-state materials for diverse photoluminescent applications and as attractive magnetic objects with the prospective application in information storage and spintronics. We present a synthetic methodology in which both luminescent and magnetic functionalities are induced within lanthanide-based coordination polymers by the application of hexacyanocobaltate(III) anions and 3-hydroxypyridine (3-OHpy), both coordinated to 4f-metal ions modulating the lanthanide-centered properties. We report a series of trimetallic cyanido-bridged chains {[Eu III x Tb III 1-x (3-OHpy) 2 (H 2 O) 4 ][Co III (CN) 6 ]}·H 2 O (x = 1, 0.8, 0.5, 0.4, 0.3, 0.2, 0.1, 0; compounds 1, 2, ..., 7, 8). They reveal tunable visible photoluminescence ranging from green, through yellow and orange, to red color depending on the composition of material and the wavelength of UV excitation light. Such multicolored emission is realized by the adjusted ratio between red emissive Eu 3+ and green emissive Tb 3+ and by the selection of wavelengths of UV light controlling the intensities of Eu- and Tb-based components of visible luminescence. The photoluminescence is enhanced by the energy-transfer (ET) process from [Co III (CN) 6 ] 3- and 3-OHpy to lanthanides, and the efficiencies of ET to Eu and Tb play an important role in the switchable emission. The whole family, 1-8, exhibits temperature-dependent paramagnetism due to the intrinsic property of lanthanide(3+) ions. Tb-containing 2-8 reveal the field-induced slow relaxation of magnetization due to the magnetic anisotropy of Tb 3+ . Moreover, the compounds built of large amounts of Tb reveal the double relaxation, the faster of a typical Tb III single-ion origin, and the slower originating from the magnetic dipole-magnetic dipole interactions between neighboring Tb III centers. Compound 2, which can be considered as a magnetically diluted sample, exhibits almost single relaxation process with the thermal energy barrier ΔE/k B of 35.8(6) K and τ 0 = 1.1(2) × 10 -8 s at H dc = 1500 Oe, indicating a single-molecule magnet behavior.