Fractal conceptualization of intumescent fire barriers, toward simulations of virtual morphologies.

By limiting the heat spread during a fire hazard, intumescent coatings are important components of passive protection systems. They swell due to heat induced reactions of micro constituents and are transformed into carbonaceous porous-like media, known as intumescent chars. Their multiscale inner structures, key elements of performance, are costly to predict by recurrent and large scale fire testing while numerical simulations are challenging due to complex kinetics.

Salen Complexes as Fire Protective Agents for Thermoplastic Polyurethane: Deep Electron Paramagnetic Resonance Spectroscopy Investigation.

The contribution of copper complexes of salen-based Schiff bases N, N'-bis(salicylidene)ethylenediamine (C1), N, N'-bis(4-hydroxysalicylidene)ethylenediamine (C2), and N, N'-bis(5-hydroxysalicylidene)ethylenediamine (C3) to the flame retardancy of thermoplastic polyurethane (TPU) is investigated in the context of minimizing the inherent flammability of TPU. Thermal and fire properties of TPU are evaluated. It is observed that fire performances vary depending upon the substitution of the salen framework.

Bio-affinity of copper(II) complexes with nitrogen and oxygen donor ligands: Synthesis, structural studies and in vitro DNA and HSA interaction of copper(II) complexes.

Reported herein the binding affinity between Human Serum Albumin and the DNA binding and cleavage activity of three copper(II) complexes, [Cu(phen)(o-van)ClO] (1), [Cu(phen)(gly)]ClO (2) and [Cu(L)(HO)] (3) wherein 1 and 2 are synthesized with 1,10-phenanthroline (phen) and co-ligands (o-van: o-vanillin; gly: glycine) and 3 with a ligand 2-hydroxy-3-methoxybenzylidene-4H-1,2,4-triazol-4-amine (HL). Complex 2 crystallizes in monoclinic (P21/n) space group shows square pyramidal geometry. The complex 3 crystallizes in monoclinic (P21/a) space group.

Fe(II) Spin Transition Materials Including an Amino-Ester 1,2,4-Triazole Derivative, Operating at, below, and above Room Temperature.

A new family of one-dimensional Fe(II) 1,2,4-triazole spin transition coordination polymers for which a modification of anion and crystallization solvent can tune the switching temperature over a wide range, including the room temperature region, is reported. This series of materials was prepared as powders after reaction of ethyl-4H-1,2,4-triazol-4-yl-acetate (αEtGlytrz) with an iron salt from a MeOH/H2O medium affording: [Fe(αEtGlytrz)3](ClO4)2 (1); [Fe(αEtGlytrz)3](ClO4)2·CH3OH (2); [Fe(αEtGlytrz)3](NO3)2·H2O (3); [Fe(αEtGlytrz)3](NO3)2 (4); [Fe(αEtGlytrz)3](BF4)2·0.5H2O (5); [Fe(αEtGlytrz)3](BF4)2 (6); and [Fe(αEtGlytrz)3](CF3SO3)2·2H2O (7).

Crossing the Traditional Boundaries: Salen-Based Schiff Bases for Thermal Protective Applications.

A broad spectrum of applications of "Salen"-based Schiff bases tagged them as versatile multifunctional materials. However, their applicability is often bounded by a temperature threshold and, thus, they have rarely been used for high temperature applications. Our investigation of a classical Schiff base, N,N'-bis(4-hydroxysalicylidene)ethylenediamine (L2), reveals that it displays an intriguingly combative response to an elevated temperature/fire scenario.

Two-step spin transition in a 1D Fe(II) 1,2,4-triazole chain compound.

A thermochromic 1D spin crossover coordination (SCO) polymer [Fe(βAlatrz)3](BF4)2⋅2 H2O (1⋅2 H2O), whose precursor βAlatrz, (1,2,4-triazol-4-yl-propionate) has been tailored from a β-amino acid ester is investigated in detail by a set of superconducting quantum interference device (SQUID), (57)Fe Mössbauer, differential scanning calorimetry, infrared, and Raman measurements. An hysteretic abrupt two-step spin crossover (T1/2(↓) = 230 K and T1/2(↑) = 235 K, and T1/2(↓) = 172 K and T1/2(↑) = 188 K, respectively) is registered for the first time for a 1,2,4-triazole-based Fe(II) 1D coordination polymer. The two-step SCO configuration is observed in a 1:2 ratio of low-spin/high-spin in the intermediate phase for a 1D chain.

Single-walled metal-organic nanotube built from a simple synthon.

A conformationally flexible triazole-carboxylic acid ligand derived from an L-amino acid, namely, 4 H-1,2,4-triazol-4-yl-acetic acid (αHGlytrz), has been exploited to synthesize a structurally diverse and functionally intriguing metal-organic framework with CuSiF6. The crystal structure reveals a novel single-walled metal-organic nanotube (SWMONT), namely, {[Cu3(μ3-OH)(H2O)3(Glytrz)3]⋅SiF6⋅8 H2O⋅X}∞ (1), (where X = disordered lattice water molecules) having a pore size as large as zeolites. Compound 1 was synthesized as crystals, as powder, or as layers by precipitation/electrodeposition.

Selective and reusable iron(II)-based molecular sensor for the vapor-phase detection of alcohols.

A mononuclear iron(II) neutral complex (1) is screened for sensing abilities for a wide spectrum of chemicals and to evaluate the response function toward physical perturbation like temperature and mechanical stress. Interestingly, 1 precisely detects methanol among an alcohol series. The sensing process is visually detectable, fatigue-resistant, highly selective, and reusable.

Crystal engineering of Fe(II) spin crossover coordination polymers derived from triazole or tetrazole ligands.

The past decade has witnessed intense research activity in the area of Fe(II) spin crossover coordination polymers, which are structurally diverse and functionally intriguing materials. In this endeavor, a less exploited series of ligands have been selected among various N-donor triazole and tetrazole molecules. Developing conventions that allow the tailoring of such functional materials with predictable architecture and properties is an important objective and current interest in crystal engineering.

Cooperative spin transition in a mononuclear manganese(III) complex.

Mind the gap: A complete, cooperative spin transition for a mononuclear Mn(III) complex is reported with an 8 K hysteresis window. Raman spectra collected at a single temperature in warming and cooling modes confirm the electronic bistability within the hysteresis loop. The source of the cooperativity is a disconnection in the hydrogen-bonded 1D chains that connect adjacent cations owing to an order-disorder transition in the PF(6)(-) counterion.

Spin transition sensors based on β-amino-acid 1,2,4-triazole derivative.

A β-aminoacid ester was successfully derivatized to yield to 4H-1,2-4-triazol-4-yl-propionate (βAlatrz) which served as a neutral bidentate ligand in the 1D coordination polymer [Fe(βAlatrz)(3)](CF(3)SO(3))(2)·0.5H(2)O (1·0.5H(2)O).

Spin transition charted in a fluorophore-tagged thermochromic dinuclear iron(II) complex.

The first crystal structures of a dinuclear iron(II) complex with three N1,N2-1,2,4-triazole bridges in the high-spin and low-spin states are reported. Its sharp spin transition, which was probed using X-ray, calorimetric, magnetic, and (57)Fe Mossbauer analyses, is also delineated in the crystalline state by variable-temperature fluorimetry for the first time.

Cooperative spin transition in a lipid layer like system.

A novel iron(II) mononuclear spin transition complex [FeL(py)(2)] displays an abrupt spin transition around 225 K accompanied by a very wide thermal hysteresis loop (∼50 K) that spreads out over 100 K. Crystal structure analysis in both low-spin and high-spin states reveals a lipid layer-like arrangement of the complex molecules and provides insights into the spin switching mechanism.

Vibrational properties of the trinuclear spin crossover complex [Fe3(4-(2'-hydroxy-ethyl)-1,2,4-triazole)6(H2O)6](CF3SO3)6: a nuclear inelastic scattering, IR, Raman and DFT study.

The vibrational properties of the trimeric iron complex [Fe(3)(4-(2'-hydroxy-ethyl)-1,2,4-triazole)(6)(H(2)O)(6)](CF(3)SO(3))(6) which serves as a model of the 1D iron coordination polymers based on 1,2,4-triazoles have been investigated by nuclear inelastic scattering of synchrotron radiation (NIS), as well as by Raman and infrared (IR) spectroscopy. The system reveals a soft spin crossover involving only the central iron atom with its FeN(6) core, while the terminal FeN(3)O(3) units show no spin transition. The NIS spectra of the central low-spin isomer exhibit a number of marker bands in the 350-450 cm(-1) region which have not been detected in the Raman spectra.

Insights into the origin of cooperative effects in the spin transition of [Fe(NH2trz)3](NO3)2: the role of supramolecular interactions evidenced in the crystal structure of [Cu(NH2trz)3](NO3)2.H2O.

The thermally induced hysteretic spin transition (ST) that occurs in the polymeric chain compound [Fe(NH(2)trz)(3)](NO(3))(2) (1) above room temperature (T(c)(upward arrow) = 347 K, T(c)(downward arrow) = 314 K) has been tracked by (57)Fe Mössbauer spectroscopy, SQUID magnetometry, differential scanning calorimetry (DSC), and X-ray powder diffraction (XPRD) at variable temperatures. From the XRPD pattern indexation, an orthorhombic primitive cell was observed with the following cell parameters: a = 11.83(2) A, b = 9.

Electronic and structural aspects of spin transitions observed by optical microscopy. The case of [Fe(ptz)6](BF4)2.

The colorimetric analysis of images recorded with an optical microscope during the onset of the spin crossover transformation allows monitoring separately the involved electronic and structural aspects, through the separation of resonant absorption and scattering effects. Complementary information can also be obtained by using the polarized modes of the microscope. These potentialities are illustrated by the observation of [Fe(ptz)(6)](BF(4))(2) single crystals during the onset of the thermal transitions in the 110-140 K range.

Insights into the origin of solid-state photochromism and thermochromism of N-salicylideneanils: the intriguing case of aminopyridines.

The relationships between the crystal structure and optical properties of switchable N-salicylideneanils have been revised and discussed on the basis of new experimental results and a computational approach. N-salicylidene-3-aminopyridine (L(3)) is a versatile thermo- and photochromic molecule. It also exhibits an infinitely slow thermal back relaxation (k = 9.

The stereochemical diversity of a new SNONS binucleating ligand towards 3d metal ions.

A new binucleating ligand containing phenoxide as an endogenous bridging group, 2,6-diformyl-p-cresol bis(2-furanthiocarboxyhydrazone) and its binuclear Co(II), Ni(II), Cu(II) and Zn(II) complexes with chloride ion as an exogenous bridge, have been obtained. The complexes were characterized by elemental analysis, molar conductivities, magnetic moment measurements at room temperature, electronic, IR, 1H-NMR, EPR, FAB spectral studies and thermal data. The copper complex assumes a tetranuclear structure composed of two binuclear units related by a center of symmetry.