Metal–organic frameworks (MOFs) or porous coordination polymers (PCPs) are open, crystalline supramolecular coordination architectures with porous facets. These chemically tailorable framework materials are the subject of intense and expansive research, and are particularly relevant in the fields of sensory materials and device engineering. As the subfield of MOF-based sensing has developed, many diverse chemical functionalities have been carefully and rationally implanted into the coordination nanospace of MOF materials. MOFs with widely varied fluorometric sensing properties have been developed using the design principles of crystal engineering and structure–property correlations, resulting in a large and rapidly growing body of literature. This work has led to advancements in a number of crucial sensing domains, including biomolecules, environmental toxins, explosives, ionic species, and many others. Furthermore, new classes of MOF sensory materials utilizing advanced signal transduction by devices based on MOF photonic crystals and thin films have been developed. This comprehensive review summarizes the topical developments in the field of luminescent MOF and MOF-based photonic crystals/thin film sensory materials.

Metal-organic frameworks: functional luminescent and photonic materials for sensing applications.

The purpose of this critical review is to give a representative and comprehensive overview of the arising developments in the field of magnetic metal–organic frameworks, in particular those containing cobalt(II). We examine the diversity of magnetic exchange interactions between nearest-neighbour moment carriers, covering from dimers to oligomers and discuss their implications in infinite chains, layers and networks, having a variety of topologies. We progress to the different forms of short-range magnetic ordering, giving rise to single-molecule-magnets and single-chain-magnets, to long-range ordering of two- and three-dimensional networks (323 references).

Magnetic metal-organic frameworks.

: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Polyoxometalates (POMs) are discrete anionic metaloxygen clusters which can be regarded as soluble oxide fragments. They exhibit a great diversity of sizes, nuclearities, and shapes. They are built from the connection of {MOx} polyhedra, M being a d-block element in high oxidation state, usually VIV,V, MoVI, or WVI.1 While these species have been known for almost two centuries, they still attract much interest partly based on their large domains of applications. They play a great role in various areas ranging from catalysis,2 medicine,3 electrochemistry,4 photochromism,5 to magnetism.6 This palette of applications is intrinsically due to the combination of their added value properties (redox properties, large sizes, high negative charges, nucleophilicity...). Parallel to this domain, the organic-inorganic hybrids area has followed a similar expansion during the last 10 years. The concept of organic-inorganic hybrid materials * To whom correspondence should be addressed. E-mail: dolbecq@ chimie.uvsq.fr. Chem. Rev. 2010, 110, 6009–6048 6009

Hybrid Organic−Inorganic Polyoxometalate Compounds: From Structural Diversity to Applications

Iron Catalysis in Organic Synthesis

As a consequence of increasing global energy demand and depleting fossil fuels, artificial photosynthesis, i.e., subsequent photocatalytic water oxidation and CO2 reduction, has become significant for providing renewable energy. To...

En route to Artificial Photosynthesis: The Role of Polyoxometalate Based Photocatalysts

In this work, we report three isostructural Fe4Ln4 wheel type complexes with molecular formula [{Fe4(dea)4Dy4(deaH)8(μ2-OMe)4}(NO3)4]·4(H2O) (1), [{Fe4(dea)4Gd4(deaH)8(μ2-OMe)4}·(NO3)4]·4(H2O)·4(MeOH) (2) and [{Fe4(dea)4Y4(deaH)8(μ2-OMe)4}(NO3)4]·4(H2O)·6(MeOH) (3), (where dea = diethanolamine). Detailed structural analysis discloses that the 4LnIII and 4FeIII ions are connected alternatively in a cyclic arrangement through the oxo-bridging of methanol and diethanolamine molecules. The detailed magnetic measurements reveal the presence of ferromagnetic exchange interactions between the LnIII and FeIII centers in complexes 1 and 2, whereas a weak antiferromagnetic interaction is observed between FeIII centers in complex 3. In addition, complex 1 shows slow magnetic relaxation behavior (Ueff = 9.8 K) under zero field and a remarkable entropy change was observed for complex 2 at 7 T magnetic field (magnetocaloric effect = 31.15 J kg−1 K−1). The ab initio calculations disclose the presence of strong axial anisotropy and a minimum transverse component (gx = 0.0024, gy = 0.0062, and gz = 19.82) in the ground state of each DyIII ion for complex 1. It was also found that the local anisotropy axis on each DyIII ion is arranged in a vortex-like structure as observed in single molecule toroics (SMTs). From BS-DFT calculations, it was found that the exchange interactions between Fe–Ln metal centers mainly follow the charge transfer process between 3d and 4f orbitals.

A new family of Fe4Ln4 (Ln = DyIII, GdIII, YIII) wheel type complexes with ferromagnetic interaction, magnetocaloric effect and zero-field SMM behavior

Two unprecedented oxonate based 1D coordination polymers with FeII and CoII have been synthesized. A detailed magnetic investigation revealed that these complexes are the first oxonate based systems to exhibit spin canted antiferromagnetic ordering at low temperatures. Proton conductivity studies of the complexes showed good proton conduction ability at elevated temperatures and under high humidity conditions.

Concomitant spin-canted antiferromagnetic ordering and proton conduction in homometallic and homoleptic coordination polymers

Study of Spin Crossover Property of a Series of X-OMe-SalEen (X=6, 5 and 4) Based Fe(III) Complexes

Two CoII based complexes namely [Co(IAP)(SCN)2] (1) and {[Co(IPEH)2(SCN)2]·H2O}n (2) (where IPEH = (((1E,2E)-1,2-bis(1-(4-(1H-imidazol-1-yl)phenyl)ethylidene)hydrazine) and IAP = (4'-(imidazol-1-yl)acetophenone)) have been synthesized and characterized by single-crystal X-ray diffraction, magnetic measurements and ab initio calculations. Structural analysis revealed that complex 1 has a zero-dimensional mononuclear structure and complex 2 has a two-dimensional framework where the CoII centers are bridged by bis(monodentate) ligand IPEH. In both the complexes, the CoII center has a distorted octahedral geometry with a CoN6 coordination environment, formed by four equatorial N atoms from the neutral ligand and two NCS- at the axial positions. Detailed magnetic measurements reveal the presence of easy-plane magnetic anisotropy for both the complexes, whereas the field-induced slow relaxation of magnetization is observed at a relatively higher temperature in 1 (above 2 K, Ueff = 30 K) as compared to 2 (below 2 K, Ueff = 6.5 K). The ab initio calculations show the negligible effect of the first coordination sphere as similar anisotropic parameters are obtained for both the complexes. Additionally, it was found that the anisotropic axes are aligned well in a particular direction in complex 1 whereas it is randomly oriented in the framework of 2. The parallel orientation of the anisotropic axes enhances the axial anisotropy and reduces the transverse component, resulting in a higher energy barrier (Ueff = 30 K) in complex 1. The detailed analysis of field and temperature dependence of relaxation time indicates that Raman, direct and QTM processes mainly play an important role in the relaxation dynamics of complex 1.

Alignment of axial anisotropy of a mononuclear hexa-coordinated Co(II) complex in a lattice shows improved single molecule magnetic behavior over a 2D coordination polymer having a similar ligand field

Sanjit Konar

Papers

En route to Artificial Photosynthesis: The Role of Polyoxometalate Based Photocatalysts

A new family of Fe4Ln4 (Ln = DyIII, GdIII, YIII) wheel type complexes with ferromagnetic interaction, magnetocaloric effect and zero-field SMM behavior

Concomitant spin-canted antiferromagnetic ordering and proton conduction in homometallic and homoleptic coordination polymers

Study of Spin Crossover Property of a Series of X-OMe-SalEen (X=6, 5 and 4) Based Fe(III) Complexes

Alignment of axial anisotropy of a mononuclear hexa-coordinated Co(II) complex in a lattice shows improved single molecule magnetic behavior over a 2D coordination polymer having a similar ligand field