PCCP Blog

Scientists from Wuhan University of Technology have found that the visible-light absorption and photocatalytic activities of B-, C- and B/C-doped anatase TiO₂ are not only influenced by the energy gaps and the distributions of energy states, but also by the locations of Fermi levels and the energies of the band gap edges. They also found that the stability of the doped TiO2 was dependant on its growth conditions.

Jiaguo Yu, Peng Zhou and Qin Li used density functional theory calculations to investigate the structures, formation energies and electronic properties of B-, C- and B/C-doped anatase TiO2. Their study provides insights into the design and synthesis of multi-doped TiO2 with desirable electronic properties, important in areas such as heterogeneous catalysis.

Read this HOT article:

New insight into the enhanced visible-light photocatalytic activities of B-, C- and B/C-doped anatase TiO2 by first-principles
Jiaguo Yu, Peng Zhou and Qin Li
DOI: 10.1039/C3CP44651D

Remi Chauvin and Christine Lepetit give the topological resonance energy (TRE) acyclic reference of any π-cyclic molecule, for 36 years merely defined by an abstract matching polynomial, a real chemical structure: the Mobius-twisted head-to-tail metathesis cyclo-dimer of the parent ring.

The aromaticity of a cyclically conjugated molecular system can be qualitatively defined as its tendency to resist the loss of its cyclic character under constraint or relief of external perturbations, or fundamentally quantified as the difference between the energy of the cyclic system and the energy of some acyclic reference. This acyclic reference is rigorously defined as the abstract reference of the TRE, but might not exist as a chemical species. In their recent PCCP paper, Chauvin and Lepitit report the long-sought chemical nature of TRE, and of topological aromaticity.

Read the details in this HOT article today:

The fundamental chemical equation of aromaticity
Remi Chauvin and Christine Lepetit
DOI: 10.1039/C2CP44075J

Hernandez and Schmidt investigate the role of anisotropic water-carbon interactions on water in low-diameter carbon nanotubes (CNTs) in their recent PCCP paper, and demonstrate the importance of the anisotropy. Extensive simulations provide a comprehensive picture of the effects of the interaction anisotropy on the structure and dynamics of water confined in narrow, single-walled CNTs.

Carbon based materials are generally accepted as being hydrophobic, but the calculated water-graphene interaction is found to be non-negligible and, moreover, orientation-dependant. The authors firstly calibrated new parameters for a Lennard-Jones potential, emphasising the anisotropy in the carbon-water interaction. They then performed molecular dynamics studies, using these parameters, of water inside various CNTs to examine properties such as structure, Lindemann index, mean square displacements and H-bonding patterns.

In contrast to previous simulations employing spherical interaction models, they found that the water molecules tend to form denser clusters displaying liquid-like behaviour, allowing for self-diffusion along the CNT axis.

Structures and hydrogen-bonding networks of water molecules inside CNTs can be radically different to those found in bulk water, due to the fact that the water molecules are confined in tubes with diameters not much larger than their own size. A central issue in many applications of CNTs is the possibility of conveying or storing fluids, hence the importance of understanding these systems.

Read about these fascinating results in this article:

Anisotropy of the Water-Carbon Interaction: Molecular Simulations of Water in Low-Diameter Carbon Nano-Tubes
Burkhard Schmidt
DOI: 10.1039/C3CP44278K

A recent theoretical study by Zhijan Wu, Aimin Ren and co-workers predicts novel BODIPY derivatives with interesting and potentially very useful nonlinear optical properties.

The group studied a series of aza-BODIPY fluorophores with structures expected to have large two-photon cross-sections at telecommunication wavelengths. They found that it is possible to finely tune the linear and non-linear optical properties by chemical modification of the aza-BODIPY core and peripheral moieties, resulting in excellent, original candidates for nonlinear transmission and fluorescent labelling materials.

Read the full paper:

New insights into two-photon absorption properties of functionalized aza-BODIPY dyes at telecommunication wavelengths: a theoretical study
Xiaoting Liu, Jilong Zhang, Kai Li, Xiaobo Sun, Zhijian Wu, Aimin Ren and Jikang Feng
DOI: 10.1039/C3CP44435J

Janina Kneipp and co-authors report SERS spectra of hemoglobin using silver and gold nanoparticles in red blood cells in their recent PCCP paper, which shed light on the interactions of nanoparticles with red blood cells.

The group used small nanoparticle concentrations compared to the concentration of hemoglobin molecules, similar to the situation upon nanoparticle entry into the hemoglobin-rich environment of the red blood cell. They demonstrated the dependence of the SERS spectra on the type and size of nanoparticle used as the SERS substrate. They confirmed that the nanoparticles interact with blood cells via interaction with hemoglobin and are also in contact with many other red blood cell components. Interestingly, the evidence shows nanoparticle-induced structural changes in the lipid bilayer of the red blood cells.

Understanding these interactions are of great importance, as silver nanoparticles, found everywhere in everyday life, display high cytotoxicity. The uptake of nanoparticles into red blood is also intriguing as it does not occur by endocytosis.

Read the detail in this article today:

SERS reveals the specific interaction of silver and gold nanoparticles with hemoglobin and red blood cell components
Daniela Drescher, Tina Büchner, Don McNaughton and Janina Kneipp
DOI: 10.1039/C3CP43883J

If you enjoyed this article, keep an eye out for our themed issue on plasmonics and spectroscopy, which is soon to be published.

Paul Mulvaney and co-workers investigate the optical properties of an end-to-end assembly of gold nanorods in their recent PCCP paper.

The group from the University of Melbourne used optical and electron microscopy to study the scattering properties of colloidal gold nanorods aligned end-to-end via dithiol coupling at the single particle level. They found that the nanostructures exhibited polarization-dependant optical properties, due to selective excitation of collective bonding and antibonding modes.

The authors were interested in how the angle between plasmonic structures affects coupling. They examined the coupling between both gold nanorod dimers and rod-sphere-rod trimers as a function of subtended angles of the dimer and trimer. They found that the intensity of the resonance in dimers and trimers depends strongly on the angles within the assembled structure. Additionally, they determined that the coupled longitudinal surface plasmon resonance of coupled Au nanorods exhibited a red shift as the number of rods in the chain increased.

Read this HOT article today:

Surface plasmon coupling in end-to-end linked gold nanorod dimers and trimers
Jatish Kumar, Xingzhan Wei, Steven Barrow, Alison M. Funston, K. George Thomas and Paul Mulvaney
DOI: 10.1039/C3CP44657C

If you enjoyed this article you will enjoy our themed issue on optical studies of single metal nanoparticles. Take a look!