R. Scott McLean

A Room-Temperature Molecular/Organic-Based Magnet

The reaction of bis(benzene)vanadium with tetracyanoethylene, TCNE, affords an insoluble amorphous black solid that exhibits field-dependent magnetization and hysteresis at room temperature. The critical temperature could not be estimated as it exceeds 350 kelvin, the thermal decomposition temperature of the sample. The empirical composition of the reported material is V(TCNE)x�Y(CH2Cl2) with x ∼ 2 and Y ∼ 1/2. On the basis of the available magnetic and infrared data, threedimensional antiferromagnetic exchange of the donor and acceptor spins resulting in ferrimagnetic behavior appears to be the mode of magnetic coupling.

Decamethylchromocenium tetracyanoethenide, (Cr(C5Me5)2]:.+[TCNE]˙+: a molecular ferromagnet with Tc= 3.65 K

The electron-transfer salt 4[Cr(C5Me5)2]+[TCNE]˙–(TCNE = tetracyanoethylene) has been prepared and structurally characterized by single-crystal X-ray diffraction. It possesses a solid-state motif of parallel 1D chains of alternating radical rations and anions similar to, but not isostructural to, the ferromagnet [Fe(C5Me5)2]˙+[TCNE]˙–·4[Cr(C5Me5)2]+[TCNE]˙– is a soft ferromagnet with no hysteretic effects observed and Tc= 3.65 K.

Magnetic behaviour of octaethylporphyrinatomanganese(III) tetracyanoethenide, [MnOEP][TCNE], and hexacyanobutadienide, [MnOEP][C4(CN)6]: the importance of a uniform chain for stabilizing strong effective ferromagnetic coupling

[MnOEP][A]{A=[TCNE]˙– and [C4(CN)6]˙–} have been isolated as extended 1D coordination polymers with trans-µ2-[A] bridging ligands with strong {A=[C4(CN)6]˙–} and weak {A =[TCNE]˙–} ferromagnetic coupling as evidenced from the fit of the magnetic susceptibility to the Curie-Weiss law (θ= 5.1 and 67.1 K, respectively); the strong behaviour arises from the presence of uniform chains which are not present for the [TCNE]˙– salt.

Novel co-operative magnetic properties of decamethylmanganocenium 2,3-dichloro-5,6-dicyanobenzoquinoneide, 3[Mn(C5Me5)2]:+[DDQ]˙–

The electron-transfer salt 3[Mn(C5Me5)2]:+[DDQ]˙–, isomorphous to orthorhombic [Fe(C5Me5)2]˙+[DDQ]˙–, has been prepared. It exhibits a complex field-dependent magnetic pahse diagram at low temperatures with evidence for ferromagnetic coupling as well as a low moment state below 4 K for zero-field cooled samples.

Alumina Tie Layer Promotes Environmental Durability of FEP Adhesion to EVA

Adhesion of fluorinated ethylene propylene polymer (FEP) to poly(co-ethylene-vinyl acetate) (EVA) is discussed in the context of photovoltaic modules, where FEP film has the potential to improve photovoltaic efficiency when used as a sun-facing weathering layer. While virgin FEP has practically no adhesion to EVA, it is demonstrated that cementable FEP, which has a surface chemically enriched in nitrogen and oxygen, has much improved as-laminated adhesion to EVA. However, when subjected to accelerated weathering tests involving exposure to 85°C, 85% relative humidity environment, or temperature cycling to −40°C from this state, the improvement in adhesion is not well maintained. To overcome such limited durability, the benefit is shown of adding an aluminum oxide coating to cementable FEP such that when laminated, the alumina layer is sandwiched between the FEP and EVA surfaces. This structure not only has excellent as-laminated adhesion to EVA, but adhesion performance is maintained for extended accelerated weathering.