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Organic π‐scaffolds are being envisaged for new‐age electron‐ and ion‐responsive materials that can accumulate electrons as well as transport proton. However, such systems are extremely rare as electron‐deficient scaffolds are unstable in aqueous solution. Here we detail the synthesis of a water‐stable core‐naphthalenediimide‐nitrobenzyl‐viologen based tetra‐cation, which accumulates up to eight‐electrons within an exceptionally narrow potential window of +0.05 V and −1.12 V. The supramolecular interactions and the ensuing ionic framework are tunable based on the three anions, e. g. Cl−, Br− and PF6−, that are investigated in this work. The ionic framework is formed and supported by a range of H‐bonds, in which, the nitro benzyl groups act as pillars connecting the 1D water‐tapes and the halide anions. The water molecules are hydrogen‐bonded with the halide anions and bestow a facile pathway for the proton conduction, with proton conductivity up to 3.19×10−3 S cm−1. In contrast, the ionic assembly formed by the lipophilic PF6− anions do not host the water tapes and consequently the proton conductivity is found to be four orders of magnitude lower. This is a unique example, whereby proton conductivity is realized and is tunable within a highly electron‐deficient, eight‐electron acceptor, water‐stable ionic supramolecular system. [ABSTRACT FROM AUTHOR]

A well‐judged combination of a high axial ligand field and a bridging radical ligand in a dinuclear lanthanide complex provides a single‐molecule magnet with a higher effective energy barrier for magnetic relaxation and blocking temperature compared to its non‐radical analog due to significant magnetic exchange coupling between radical and Ln(III) ions. In this work, we report two chloranilate (CA) bridged dinuclear dysprosium complexes, [{(bbpen)Dy(μ2‐CA)Dy(bbpen)}] (1Dy) and [{(bbpen)Dy(μ2‐CA⋅)Dy(bbpen)}−{CoCp2}+] (2Dy), where 2Dy is the radical bridged Dy‐complex obtained via the chemical reduction of bridging CA moiety (H2bbpen=N,N′‐bis(2‐hydroxybenzyl)‐N,N′‐bis(2‐methylpyridyl)ethylenediamine). The presence of high electronegative phenoxide moiety enhances the axial anisotropy of pseudo‐square antiprismatic Dy(III) ions. The diffused spin of radical is efficiently coupled with anisotropic Dy(III) centres and decreases the quantum tunnelling of magnetization (QTM) in the magnetic relaxation process. The magnetic relaxation of 1Dy follows Orbach, Raman, and QTM processes whereas for 2Dy it follows Orbach and Raman Processes. Due to less involvement of the QTM relaxation process, 2Dy shows a higher thermal energy barrier (Ueff=700 K) and a high blocking temperature (6.7 K), compared to its non‐radical analog. Remarkably, the radical coupled 2Dy complex shows the highest energy barrier among the radical bridged Dy(III)‐based SMMs to date. [ABSTRACT FROM AUTHOR]

Multi-stimuli responsive switchable molecules have garnered interest for their potential applications in the field of magnetic materials. However, the persistent challenge lies in isolating these properties within the same material. Herein, we report a discrete [Fe2Co3] pentanuclear cyanide bridged complex, [Co(L)2]3[Fe (CN)6]2·20H2O, (1) (L = (Z)-N'-(4-(trifluoromethyl)phenyl)picolinimidamide) which undergoes electron transfer coupled spin transition (ETCST) from [FeII2CoIIHSCoIII2] to [FeIII2CoII3] configurations through thermal activation and upon protonation. [ABSTRACT FROM AUTHOR]

Inorganic nanohosts doped with lanthanide ions are an indispensable tool for multimodal bioimaging and MRI applications due to their distinctive optical, magnetic, and biocompatible properties. Nanocomposites of such nanoprobes with functionalization capabilities could also enable their use in targeted therapy‐based applications. However, the influence of nanocomponents especially their proportion in a nanocomposite in modulating the physio‐chemical and biocompatibility properties of the nanocomposite is still elusive. To address this knowledge gap, we have engineered nanocomposites variants using an environmentally benign one‐step synthesis with ionic liquids. We have synthesized two nanocomposites, differing in the proportion of lanthanide‐doped ternary fluoride nanoparticles (as nanophase material with luminescent and magnetic traits) and graphene oxide (as host matrix phase with tunable functionalization potential for theranostics applications). We found that with increased GO nanomaterial, nanocomposites showed reduced crystallite size and photoluminescence properties without significantly affecting the magnetic traits. Thus, implying nanocomponents ratio has differential effect on the nanocomposite properties. To assess biocompatibility, we have employed sensitive biomarkers such as craniofacial development, cardiac rhythm, and overall survivability of zebrafish larvae. Remarkably, biocompatibility improved when the proportion of the GO was increased within the nanocomposite as compared to when the nanocomponents were assessed individually. Our results also revealed that biocompatibility of nanocomposites also depends on the synergistic interplay between the nanocomponents due to the spatial arrangement of each nanocomponent in the nanocomposites. Overall, our study offers an intriguing avenue for tuning the biocompatibility of such nanocomposites, rendering them as an application‐independent biocompatible‐platform for theranostics applications. [ABSTRACT FROM AUTHOR]

A cyanide-bridged Fe2Co 2D sheet exhibiting electron transfer coupled spin transition (ETCST) with co-existence of magnetic ordering below 50 K is reported. The complex exhibits single-chain magnet behaviour where the uncoordinated water molecules act as an exchange-breaking impurity by allowing only a fraction of the molecule to undergo a spin state change. The paramagnetic centres prevail throughout the chain on desolvation, thereby increasing the number of correlated units in the chain. [ABSTRACT FROM AUTHOR]

Polyoxometalates (POM), as inorganic polydentate oxygen donors, provide binding opportunities for oxophilic lanthanide metal centers to construct novel Ln-substituted POM materials with exciting structures and attractive properties. Herein, we have reported four arsenotungstate [α-AsW9O33]9− based lanthanide-containing polyoxometalates [CsxK36–x{Ln6(H2O)12(α-AsW9O33)6}]·yH2O (Ln = Er (1), Gd (2), Ho (3), and Tb (4)), which are synthesized in an alkaline medium. Complexes 1–3 are the dimeric structures of [Ln3(H2O)6(α-AsW9O33)3]18− polyanions, whereas complex 4 is a hexamer of the polyanion [Tb (H2O)2(α-AsW9O33)]6− as a building unit. In all the complexes, [α-AsW9O33]9− units are staggered up and down and give rise to the chair conformation, where one [α-AsW9O33]9− unit bridges two Ln(III) centers through four μ2-oxygen and two terminal oxygen atoms, resulting in the hexagonal arrangement of lanthanides. The dynamic magnetic measurement indicates that only complex 1 exhibits slow relaxation of magnetization with an applied dc field (1500 Oe). To gain insight into the slow relaxation of magnetization in complex 1, the ligand-field parameters and the splitting of the ground-state multiplet of the Er(III) ions have been estimated. The ab initio calculation results confirm that the ground state wave function of these molecules (1, 3, and 4) is mainly composed of a mixture of mJ states, and the non-axial crystal field (CF) terms are more predominant than the axial CF term. The solid-state fluorescence spectra of 1–4 reveal that the photoexcitation O → M ligand-to-metal charge-transfer (LMCT) of arsenotungstate fragments is effectively quenched due to the spatial coordination environment around the Ln(III) ion. [ABSTRACT FROM AUTHOR]

Herein, three dinuclear iron(II) helicates bearing the molecular formula [Fe2(L1)3](ClO4)4 ⋅ 2CH3OH ⋅ 3H2O (complex 1), [Fe2(L2)3](ClO4)4 ⋅ 6CH3CN (complex 2), and [Fe2(L3)3](ClO4)4 ⋅ 0.5H2O (complex 3) have been synthesized using imidazole and pyridine‐imine‐based ligands having fluorene moiety in the backbone. A change in the ligand field strength by terminal modulation led to a change in the spin‐transition behaviour from incomplete, multi‐step to complete, around room temperature in the solid state. Spin transition behaviour has also been observed in the solution phase characterized using variable temperature 1H nuclear magnetic resonance spectroscopy (Evans method) and correlated using UV‐visible spectroscopy. Fitting the NMR data using the ideal solution model yielded the transition temperature in the order T1/2 (1)

Modulating the spin-crossover behaviour in porous coordination polymers is not only an excellent way to address the challenges associated with high-order data storage and processing, but the colour change involved in the process reveals their importance as thermal and optical sensors. Herein, we report the guest-induced regulation of the magnetic bi-stability in a Hofmann-type framework, {Fe(pina)[Pd(CN)4]} (1, pina = N-(pyridin-4-yl)isonicotinamide) from ∼26 K (for 1·3.6MeCN, complex 1), to ∼40 K (for 1·stb.4H2O, stb = stilbene, complex 2) by a subsequent change of the guest molecules from CH3CN to stilbene. While the electronic interactions stabilize the LS states through effective π⋯π stacking between the guest stilbene and the host layers, chemical pressure, i.e., the steric effect of the stilbene molecule, stabilizes the HS states, and the overall competition between them leads to the high thermal hysteresis. To explicate the spin crossover properties to be used as a potential thermal sensor, the guest-free nanoparticles of framework (1) were prepared using the reverse micelle method. Magnetic measurements reveal that the effective downsizing at the nanoscale results in a progressive downward shift with an incomplete gradual SCO behaviour, diminishing the hysteresis loop compared to the abrupt hysteretic transition found at the bulk phase. In addition, these nanoparticles are assimilated as free-standing thermochromic polymeric films as a proof of concept for thermal sensing device. The rationalization of the tunable SCO properties, along with the thermochromic behaviour, opens up a new strategy for the development of new π electron-responsive magnetic materials. [ABSTRACT FROM AUTHOR]

Tuning the bridging fashion of anilato ligand in dinuclear DyIII complexes, reveals a sizable effect on the slow relaxation of magnetization. Combined experimental and theoretical studies divulge that the geometry with high order axial symmetry (pseudo square antiprism) reduces the transverse crystal fields corresponding to QTM (quantum tunneling of magnetization) resulting in a significant increase in energy barrier (Ueff=518 cm-1) through the Orbach relaxation process whereas the geometry with lower symmetry (triangular dodecahedron, pseudo D2d) enhances the transverse crystal fields that accelerate the ground state QTM process. Notably, the value 518 cm-1 represents the highest energy barrier among anilato ligand based SMMs. [ABSTRACT FROM AUTHOR]

Spin crossover complexes that reversibly interconvert between two stable states imitate a binary state of 0 and 1, delivering a promising possibility to address the data processing concept in smart materials. Thus, a comprehensive understanding of the modulation of magnetic transition between high spin and low spin and the factors responsible for stabilizing the spin states is an essential theme in modern materials design. In this context, the present review attempts to provide a concise outline of the design strategy employed at the molecular level for fine‐tuning the spin‐state switching in FeII‐based Hofmann‐type coordination polymers and their effects on the optical and magnetic response. In addition, development towards the nanoscale architectures of HCPs, i. e. in terms of nanoparticles and thin films, are emphasized to bridge the gap between the laboratory and reality. [ABSTRACT FROM AUTHOR]