Jens B. Ravnsbæk

Wireless gas detection with a smartphone via rf communication

Significance This paper describes the first example of an adaption of near-field communication (NFC) technology—in 0.5 billion modern smartphones and mobile devices installed in 2014—toward portable, wireless, non-line-of-sight gas phase chemical sensing. We demonstrate the ability to convert inexpensive commercial NFC tags into chemical sensors that detect and discriminate analytes at part-per-thousand and part-per-million concentrations. This effort merges rational design of conductive nanostructured materials for selective chemical sensing with portable and widely distributed NFC technology to deliver a new method of acquiring chemical information about an NFC tag’s local environment. This paper introduces a concept for distributed chemical sensing by the growing number of people that carry NFC-enabled smartphones, tablets, and other smart devices. Chemical sensing is of critical importance to human health, safety, and security, yet it is not broadly implemented because existing sensors often require trained personnel, expensive and bulky equipment, and have large power requirements. This study reports the development of a smartphone-based sensing strategy that employs chemiresponsive nanomaterials integrated into the circuitry of commercial near-field communication tags to achieve non-line-of-sight, portable, and inexpensive detection and discrimination of gas-phase chemicals (e.g., ammonia, hydrogen peroxide, cyclohexanone, and water) at part-per-thousand and part-per-million concentrations.

Tuning The Quantum Yield of Fluorescent 2,5-Disubstituted-1,3a,6a-triazapentalene

Significance: Rational design of organic molecules with improved photo-physical properties, such as high quantum yields and tunable fluorescence wavelength, is of great interest in modern science and technology. In this paper, the authors report a one-pot synthesis of 2,5-disubstituted1,3a,6a-triazapentalenes. By a cascade sequence utilizing a copper(I)-catalyzed 1,3-dipolar cycloaddition followed by intramolecular cyclization and elimination, the authors managed to obtain the desired 1,3a,6a-triazapentalene skeleton. Comment: The authors report the synthesis of a series of 2,5-disubstituted-1,3a,6a-triazapentalenes. These novel compounds allowed the authors to probe the effects of electron-donating and -withdrawing substituents on the photo-physical properties of 1,3a,6a-triazapentalene derivatives. Introduction of substituents in the 5-position led to a dramatically increased quantum yield. A correlation between the Hammet σp-value of the R2-substituent and the quantum-yield tendency could furthermore be estimated. N N N

A Simple Methodology Yielding Nitriles from Alcohols

Significance: Nitriles serve an important role in many chemical compounds ranging from pharmaceuticals to organic electronic materials. In the development of new n-type semiconducting organic materials easy access to nitrile-containing starting materials is vital. In this paper, the authors report a novel method for the synthesis of nitriles from alcohols using mild reaction conditions. The methodology utilizes cheap, commercially available reagents, CuI, bipyridine, TEMPO, oxygen and aliphatic or aromatic alcohols. Comment: The authors describe a novel protocol for the conversion of aliphatic and aromatic alcohols into the corresponding nitriles utilizing mild reaction conditions. The double aerobic dehydrogenation proceeds under mild conditions for aromatic alcohols in ethanol at room temperature, while aliphatic alcohols require the use of acetonitrile at 50 °C. The protocol has a broad functional group tolerance and produces the desired nitriles in high to excellent yields. N H H