PCCP Blog

PCCP ‘HOT’ article – Exposure to humidity leads to metal ion concentrations of up to one per 4.7 polymer units

The stability of a common interface used in organic photovoltaic cells, between the transparent electrode of Indium Tin Oxide (ITO) and the polymer buffer layer (PEDOT:PSS) is strongly influenced by the presence of humidity during processing. This leads to significant migration of indium and tin species into the PEDOT:PSS layer.

Role of humidity on indium and tin migration in organic photovoltaic devices
Anirudh Sharma, Gunther Andersson and David A. Lewis
Phys. Chem. Chem. Phys., 2011, DOI: 10.1039/C0CP02203A

Canadian scientists have, for the first time, been able to identify spectroscopically carbon dioxide clusters that could provide valuable information on intermolecular interactions.

Despite the significance of carbon dioxide in atmospheric chemistry and use of supercritical carbon dioxide as an industrial solvent, the spectroscopic identification and study of carbon dioxide clusters have so far been limited to the dimer and trimer, as larger clusters can break up when being analysed.

Now, Robert McKellar and his team at the University of Calgary and the Steacie Institute for Molecular Sciences, Ontario, have identified (CO₂)₆ to (CO₂)₁₃ clusters using high resolution infrared (IR) spectroscopy, as published in their latest PCCP paper.

‘Studying clusters is a very good way of getting a handle on that because if we build up the cluster and measure its properties, then we’re really learning about the intermolecular forces in a direct way,‘ says McKellar.

Read the rest of the Chemistry World article by Yuandi Li…

Read the PCCP article:
Spectroscopic identification of carbon dioxide clusters: (CO2)6 to (CO2)13
J. Norooz Oliaee, M. Dehghany, N. Moazzen-Ahmadi and A. R. W. McKellar
Phys. Chem. Chem. Phys., 2011, 13, 1297-1300

‘HOT’ Perspective feature article – catalytic MOFs

This feature article summarises the unique properties of metal–organic frameworks (MOFs) and discusses their potential as catalysts.

The authors explore the idea that MOFs have the potential to catalyze any number of new reactions:

“We experience a unique opportunity to imagine and design heterogeneous catalysts, which might catalyze reactions previously thought impossible.”

Catalysis by metal–organic frameworks: fundamentals and opportunities
Marco Ranocchiari and Jeroen Anton van Bokhoven
Phys. Chem. Chem. Phys., 2011, DOI: 10.1039/C0CP02394A

They categorise three classes of MOF catalysts:

1. those with active site on the framework
2. those with encapsulated active species
3. those with active sites attached through post-synthetic modification

The authors also identify the unique characteristics that distinguish MOFs from other materials:

• tunable porosity
• the ability to fine tune the structure of the active site and its environment
• the presence of multiple active sites
• the opportunity to synthesize structures in which key–lock bonding of substrates occurs

PCCP Perspective article – Hot off the press!

A new class of variational states based on a tensor network approach is examined for application in transition metal chemistry.

New electron correlation theories for transition metal chemistry
Konrad H. Marti and Markus Reiher
Phys. Chem. Chem. Phys., 2011, DOI: 10.1039/C0CP01883J

Electronic structure theory faces many computational challenges in transition metal chemistry. Usually, density functional theory is the method of choice for theoretical studies on transition metal complexes and clusters mostly because it is the only feasible one, although its results are not systematically improvable. By contrast, multireference ab initio  methods could provide a correct description of the electronic structure, but are limited to small molecules because of the tremendous computational resources required. In recent years, conceptually new ab initio  methods emerged that turned out to be promising for theoretical coordination chemistry.

Two efficient parametrization schemes are discussed for the electronic wave function, the matrix product states and the complete-graph tensor network states. Their advantages are demonstrated at example transition metal complexes. Especially, tensor network states might provide the key to accurately describe strongly correlated and magnetic molecular systems in transition metal chemistry.

Perspective review article – using mass spectrometry to understand organic aerosols

Understanding the molecular composition and fundamental chemical transformations of organic aerosols (OA) during their formation and lifetime is a major challenge in atmospheric research.

This Perspective review by Sergey Nizkorodov and colleagues dissucess the recent advances and perspectives for future research on the chemical characterization of organic aerosols using high-resolution mass spectrometry.

Read this feature article today:

Molecular chemistry of organic aerosols through the application of high resolution mass spectrometry
Sergey A. Nizkorodov, Julia Laskin and Alexander Laskin
Phys. Chem. Chem. Phys., 2011, DOI: 10.1039/C0CP02032J

‘HOT’ paper – magnetic field effects

In this paper, the magnetic field effects on the exciplex and locally excited fluorophore emission are explored. The results confirm reversibility in the excited state and the novel three-state model is also used to rationalize the extent of the magnetic field effects for different energetic situations.

Comparing the experimental emission bands with those predicted by the model, a semi-quantitative picture of the magnetic field effect has been developed.

Magnetic field effects on exciplex-forming systems: the effect on the locally excited fluorophore and its dependence on free energy
Daniel R. Kattnig, Arnulf Rosspeintner and Günter Grampp
Phys. Chem. Chem. Phys., 2011, DOI: 10.1039/C0CP01517B

‘HOT’ Perspective article

A complete computational approach for calculating molecular properties involving any element in the periodic table

This article accounts some of the recent advances in the development of ab initio methods for the calculation of molecular response properties, involving electric, magnetic, and geometric perturbations.

Feature article
The ab initio calculation of molecular electric, magnetic and geometric properties
Radovan Bast, Ulf Ekström, Bin Gao, Trygve Helgaker, Kenneth Ruud and Andreas J. Thorvaldsen
Phys. Chem. Chem. Phys., 2011, DOI: 10.1039/C0CP01647K

‘HOT’ paper – using confocal fluorescence microscopy to view zeolite crystals

Bert  Weckhuysen and Lukasz Karwacki have combined UV-Vis/confocal fluorescence micro-spectroscopy to allow in situ mapping of the template decomposition process in large zeolite ZSM-5 crystals.

New insight in the template decomposition process of large zeolite ZSM-5 crystals: an in situ UV-Vis/fluorescence micro-spectroscopy study
Lukasz Karwacki and Bert M. Weckhuysen
Phys. Chem. Chem. Phys., 2011, DOI: 10.1039/C0CP02220A

Seeing small differences in the diffusion rate of the molecules by confocal fluorescence microscopy in the porous catalyst body allowed visualization of the internal architecture of zeolite crystals and confirmed the presence of a 90 degree intergrowth structure within large ZSM-5 crystals.