Spin Crossover in Fe(II)–M(II) Cyanoheterobimetallic Frameworks (M = Ni, Pd, Pt) with 2‑Substituted Pyrazines

Discovery of spin-crossover (SCO) behavior in the family of Fe^II-based Hofmann clathrates has led to a “new rush” in the field of bistable molecular materials. To date this class of SCO complexes is represented by several dozens of individual compounds, and areas of their potential application steadily increase. Starting from Fe²⁺, square planar tetracyanometalates M^II(CN)₄^2– (M^II = Ni, Pd, Pt) and 2-substituted pyrazines Xpz (X = Cl, Me, I) as coligands we obtained a series of nine new Hofmann clathrate-like coordination frameworks. X-ray diffraction reveals that in these complexes Fe^II ion has a pseudo-octahedral coordination environment supported by four μ₄-tetracyanometallates forming its equatorial coordination environment. Depending on the nature of X and M, axial positions are occupied by two 2X-pyrazines (X = Cl and M^II = Ni (<b>1</b>), Pd (<b>2</b>), Pt (<b>3</b>); X = Me and M^II = Ni (<b>4</b>), Pd (<b>5</b>)) or one 2X-pyrazine and one water molecule (X = I and M^II = Ni (<b>7</b>), Pd (<b>8</b>), Pt (<b>9</b>)), or, alternatively, two distinct Fe^II positions with either two pyrazines or two water molecules (X = Me and M^II = Pt (<b>6</b>)) are observed. Temperature behavior of magnetic susceptibility indicates that all compounds bearing FeN₆ units (<b>1</b>–<b>6</b>) display cooperative spin transition, while Fe^II ions in N₅O or N₄O₂ surrounding are high spin (HS). Structural changes in the nearest Fe^II environment upon low-spin (LS) to HS transition, which include ca. 10% Fe–N distance increase, lead to the cell expansion. Mössbauer spectroscopy is used to characterize the spin state of all HS, LS, and intermediate phases of <b>1</b>–<b>9</b> (see abstract figure). Effects of a pyrazine substituent and M^II nature on the hyperfine parameters in both spin states are established

Spin Crossover in Fe(II)–M(II) Cyanoheterobimetallic Frameworks (M = Ni, Pd, Pt) with 2‑Substituted Pyrazines

Discovery of spin-crossover (SCO) behavior in the family of Fe^II-based Hofmann clathrates has led to a “new rush” in the field of bistable molecular materials. To date this class of SCO complexes is represented by several dozens of individual compounds, and areas of their potential application steadily increase. Starting from Fe²⁺, square planar tetracyanometalates M^II(CN)₄^2– (M^II = Ni, Pd, Pt) and 2-substituted pyrazines Xpz (X = Cl, Me, I) as coligands we obtained a series of nine new Hofmann clathrate-like coordination frameworks. X-ray diffraction reveals that in these complexes Fe^II ion has a pseudo-octahedral coordination environment supported by four μ₄-tetracyanometallates forming its equatorial coordination environment. Depending on the nature of X and M, axial positions are occupied by two 2X-pyrazines (X = Cl and M^II = Ni (<b>1</b>), Pd (<b>2</b>), Pt (<b>3</b>); X = Me and M^II = Ni (<b>4</b>), Pd (<b>5</b>)) or one 2X-pyrazine and one water molecule (X = I and M^II = Ni (<b>7</b>), Pd (<b>8</b>), Pt (<b>9</b>)), or, alternatively, two distinct Fe^II positions with either two pyrazines or two water molecules (X = Me and M^II = Pt (<b>6</b>)) are observed. Temperature behavior of magnetic susceptibility indicates that all compounds bearing FeN₆ units (<b>1</b>–<b>6</b>) display cooperative spin transition, while Fe^II ions in N₅O or N₄O₂ surrounding are high spin (HS). Structural changes in the nearest Fe^II environment upon low-spin (LS) to HS transition, which include ca. 10% Fe–N distance increase, lead to the cell expansion. Mössbauer spectroscopy is used to characterize the spin state of all HS, LS, and intermediate phases of <b>1</b>–<b>9</b> (see abstract figure). Effects of a pyrazine substituent and M^II nature on the hyperfine parameters in both spin states are established

Spin Crossover in Fe(II)–M(II) Cyanoheterobimetallic Frameworks (M = Ni, Pd, Pt) with 2‑Substituted Pyrazines

Discovery of spin-crossover (SCO) behavior in the family of Fe^II-based Hofmann clathrates has led to a “new rush” in the field of bistable molecular materials. To date this class of SCO complexes is represented by several dozens of individual compounds, and areas of their potential application steadily increase. Starting from Fe²⁺, square planar tetracyanometalates M^II(CN)₄^2– (M^II = Ni, Pd, Pt) and 2-substituted pyrazines Xpz (X = Cl, Me, I) as coligands we obtained a series of nine new Hofmann clathrate-like coordination frameworks. X-ray diffraction reveals that in these complexes Fe^II ion has a pseudo-octahedral coordination environment supported by four μ₄-tetracyanometallates forming its equatorial coordination environment. Depending on the nature of X and M, axial positions are occupied by two 2X-pyrazines (X = Cl and M^II = Ni (<b>1</b>), Pd (<b>2</b>), Pt (<b>3</b>); X = Me and M^II = Ni (<b>4</b>), Pd (<b>5</b>)) or one 2X-pyrazine and one water molecule (X = I and M^II = Ni (<b>7</b>), Pd (<b>8</b>), Pt (<b>9</b>)), or, alternatively, two distinct Fe^II positions with either two pyrazines or two water molecules (X = Me and M^II = Pt (<b>6</b>)) are observed. Temperature behavior of magnetic susceptibility indicates that all compounds bearing FeN₆ units (<b>1</b>–<b>6</b>) display cooperative spin transition, while Fe^II ions in N₅O or N₄O₂ surrounding are high spin (HS). Structural changes in the nearest Fe^II environment upon low-spin (LS) to HS transition, which include ca. 10% Fe–N distance increase, lead to the cell expansion. Mössbauer spectroscopy is used to characterize the spin state of all HS, LS, and intermediate phases of <b>1</b>–<b>9</b> (see abstract figure). Effects of a pyrazine substituent and M^II nature on the hyperfine parameters in both spin states are established

Spin Crossover in Fe(II)–M(II) Cyanoheterobimetallic Frameworks (M = Ni, Pd, Pt) with 2‑Substituted Pyrazines

Discovery of spin-crossover (SCO) behavior in the family of Fe^II-based Hofmann clathrates has led to a “new rush” in the field of bistable molecular materials. To date this class of SCO complexes is represented by several dozens of individual compounds, and areas of their potential application steadily increase. Starting from Fe²⁺, square planar tetracyanometalates M^II(CN)₄^2– (M^II = Ni, Pd, Pt) and 2-substituted pyrazines Xpz (X = Cl, Me, I) as coligands we obtained a series of nine new Hofmann clathrate-like coordination frameworks. X-ray diffraction reveals that in these complexes Fe^II ion has a pseudo-octahedral coordination environment supported by four μ₄-tetracyanometallates forming its equatorial coordination environment. Depending on the nature of X and M, axial positions are occupied by two 2X-pyrazines (X = Cl and M^II = Ni (<b>1</b>), Pd (<b>2</b>), Pt (<b>3</b>); X = Me and M^II = Ni (<b>4</b>), Pd (<b>5</b>)) or one 2X-pyrazine and one water molecule (X = I and M^II = Ni (<b>7</b>), Pd (<b>8</b>), Pt (<b>9</b>)), or, alternatively, two distinct Fe^II positions with either two pyrazines or two water molecules (X = Me and M^II = Pt (<b>6</b>)) are observed. Temperature behavior of magnetic susceptibility indicates that all compounds bearing FeN₆ units (<b>1</b>–<b>6</b>) display cooperative spin transition, while Fe^II ions in N₅O or N₄O₂ surrounding are high spin (HS). Structural changes in the nearest Fe^II environment upon low-spin (LS) to HS transition, which include ca. 10% Fe–N distance increase, lead to the cell expansion. Mössbauer spectroscopy is used to characterize the spin state of all HS, LS, and intermediate phases of <b>1</b>–<b>9</b> (see abstract figure). Effects of a pyrazine substituent and M^II nature on the hyperfine parameters in both spin states are established

Interaction of physical fields with nanostructured materials

Research results of several important material systems presented in this collective monograph demonstrate a number of characteristic features and unique effects. The main findings are listed below. 1. The interaction between molecules and semiconductor structures allows a new amplification effect to be registered and studied by utilizing a new parameter – characteristic time constant, which is extremely sensitive for the characterization of biomolecular quantity. 2. The effects of the interaction of magnetic, optical and electromagnetic fields with nanostructured composites, semiconductor structures, anisotropic media, magnetic fluid systems, layered structures, phonons of molecular nanocomplexes and nanoinhomogeneities of rough surfaces were established. 3. The fundamental nature of the interaction effects was found as a result of a careful comparison of modeling results with experimental data. The importance of the studies is underlined by the wide range of potential applications. For the reader’s convenience, the presentation of the material is structured as follows. The general content includes only the names of sections. The full content of each section is listed in the text. For the same reason, the list of references is given at the end of each section. The authors present the material in such a way that the reader can easily view the current state of research in these areas and be able to navigate freely in the text. Section 1 presents a number of effects registered in semiconductor structures with dielectric coatings as surface potential sensors. In particular, the effects of internal amplification in semiconductor (bio)sensors using single trap phenomena are revealed. The noise characteristics of semiconductor nanoscale sensor structures, the effect of γ-radiation on the noise and transport characteristics of the sensors mentioned above were analyzed. It is demonstrated that effects related to single traps can be used for the detection of troponin biomolecules as indicators of [...