Super-resolution imaging methods based on single-molecule localization are reviewed. The use of such methods to successfully study various cellular structures in fixed and living cells with quite recently unforeseeable optical resolution is demonstrated. Applications to three-dimensional imaging are also highlighted.

Lights out! A systematic study demonstrates DNA nucleotide and amino acid interference with the fluorescence emission of quantum dots. Significantly, knowledge of the specific quenching of quantum dot fluorescence is useful for experimental design in biological samples and may be of interest for future applications in analytical chemistry.

The First International Collaborative and Cooperative Chemistry Symposium (1-ICCCS) took place on the 15th and 16th November 2010 at the National University of Singapore. This is one of a number of symposia designed to foster collaborations in which chemists from Asia and the Asia-Pacific region are brought together to discuss recent advances in all fields of chemistry. Contributions from participants at the 1-ICCCS, the theme of which was Frontiers in Molecular Design and Synthesis, make up the Research Front in this issue of AJC.

Soluble and stable higher order acenes and fused acenes are prepared by modern synthetic chemistry. Both show near-infrared absorption and emission with promising applications for organic electronic devices, solar cells, and bio-imaging.

The rate-accelerating effects of fluoroalcohols for generating trivalent hypervalent iodine species and the conversion into diaryliodonium(iii) salts have been used for realizing a facile and clean one-pot synthesis of diaryliodonium(iii) salts 3 from aryl iodides 1 with peracetic acid. The scope and limitations of the methodology are elucidated.

This paper reports a direct, five step, biocompatible synthesis of the β-1,6-linked disaccharide of N-acetylglucosamine. This disaccharide is the repeat unit of the linear biopolymer which is the major constituent of bacterial biofilms.

Herein we developed a synthetic methodology to prepare collections of trisubstituted aryl 1,3,5-triazines with broad structural diversity via Suzuki coupling. Furthermore, we adapted this approach to polymer-supported amino acids and prepared aryl triazines with different charge distribution. With a collection of 160 aryl triazine derivatives in good purities and without any purification step, we proved the viability of this orthogonal scheme for the preparation of triazine libraries using amine/amino acid-captured solid supports and Suzuki cross-coupling.

Two steroidal saponins, one previously unreported, were isolated from the roots of an Australian yam Dioscorea sp. by RP-HPLC and their structures determined as 1β-hydroxyprotogracillin (1) and protogracillin (2) through a combination of 1D and 2D NMR, MS-MS and chemical degradation.

The syntheses, crystal structures, and properties of three new coordination complexes [Bu₄N][M^III(btdt)₂] [M = Cu (1), Au (2)] and [Bu₄N]₂[Pt^II(btdt)₂] (3) ({btdt}^2– = 2,1,3-benzenethiadiazole-5,6-dithiolate) are described. Interactions in the solid-state for compounds 1–3 are characterized by intermolecular contacts. The cyclic voltammetric studies of 1 exhibit a very low reduction potential for a Cu^III-coordination complex.

A catalytic CuCl₂ and DBU system promotes the coupling of terminal alkynes. Using this catalytic system homo and heterocoupling of terminal alkynes could be carried out.

Novel biotin-cholesterol conjugates were designed and synthesized which exhibited mesomorphic character, as evidenced by their optical properties. The interaction of avidin protein with these conjugates resulted in a loss of birefringence suggesting that such constructs could be used for optical detection of biological interactions.

The 2-mesityl-1,8-naphthyridine (Mes-NP) ligand keeps the Rh–Rh single bond intact, but oxidatively cleaves the Ru–Ru single bond, resulting in a Ru(II) compound; the catalytic efficacy of the latter compound has been evaluated.

Molecular imaging noninvasively quantifies and visualizes biological processes as they occur in context, ranging in scale from subcellular to whole organism using external imaging devices. Molecular probes (contrast agents) can be constitutively active or activatable, providing signal-to-background ratios that determine target conspicuity. Activatable probes limit nonspecific and off-target signal, thereby producing greater target contrast with enhanced kinetics.

Raman spectroscopy is a powerful tool for visualizing chemical distributions at high spatial resolution in a wide range of samples. Recent technical advances have reduced the time needed for Raman mapping, while the insensitivity to water makes it particularly attractive for biological applications. This review of recent studies of red blood cells highlights the analytical and diagnostic potential of Raman imaging.

The ability of a luminescent Tb(III) cyclen based complex, incorporating the Ca²⁺ iminodiacetate receptor unit, to selectively bind to regions of damaged bone structure (microdamage) and therefore, using laser-scanning confocal microscopy, provide a significant contrast from the remaining healthy bone surfaces is described.

The water soluble tetraguanidinium squaraine rotaxane endoperoxide was prepared by photooxidation and shown to undergo a thermal cycloreversion reaction that releases singlet oxygen and produces near-infrared emission. Cell toxicity assays in the dark showed no toxicity due to the released singlet oxygen, suggesting that these compounds have promise as chemiluminescent probes for in vivo molecular imaging.

Raman spectroscopic imaging is used to identify spatially varying concentrations of cholesterol and docosahexaenoyl lipids in the retinal rod outer segment (ROS). Analysis of the spectra provides direct observations of the biomolecular gradients along the ROS that had been reported by extractions and secondary indicators.

Gadolinium doped mesoporous silica (gadolinosilicate) nanoparticles were synthesized by a novel approach using gadolinium based ionic liquid emulsions aimed at incorporating Gd ions into a porous silica network, developing a potential contrast agent for (magnetic resonance imaging) MRI. Proton relaxivity results indicated that the gadolinium doped silicates had slightly lower longitudinal relaxivity and much higher transverse relaxivity than the Magnevist®.

Modern chemistry made it possible to develop target-specific noninvasive agents and monitor the interaction of tumour growth pattern, tumour neovasculature formation, and tumour cells uptake of specific agents into disease compartment at the same time. Such information is important to study tumour biological progression and potential interactions with imaging/therapeutic agents.

Infrared spectra and ab initio calculations are presented for F^–-(HCCH)_n clusters, n = 3–6. Structures predicted at the MP2 level of theory are highly symmetric with acetylene ligands equally spaced about a central fluoride anion. Predicted H-bonded C-H stretching frequencies agree well with the experimental band positions.

A thienyl structural analogue of NTBC can easily be synthesized by a new one-pot strategy in high yields using ultrasound irradiation. This compound was used to prepare indazolone and benzisoxazolone derivatives in a very simple procedure.

The Heck reaction is successfully extended to the bromochromones with an adjacent protected phenolic hydroxy group. Benzyl proves to be the ideal protecting group which could be selectively cleaved by boron trihalides. This offers a new methodology to various naturally occurring derivatives with a resacetophenone-type substitution pattern including tricyclic O-heterocycles.

This paper reports the strategy of electrochemically reductive adsorption of aryldiazonium salts on electrodes for designing stable sensing interface. The diazonium salt chemistry can serve as alternative system to alkanthiol-gold chemistry for modification of electrode surfaces for biosensor applications.