Mass spectrometry of intact synthetic polymers has been limited to field desorption (FD) MS for many years. More recently, soft ionization techniques such as electrospray (ESI) and matrix-assisted laser desorption/ionization (MALDI) and the revival of time-of-flight analyzers created new opportunities for the characterization of polymers. In this review emphasis is put on MALDI time-of-flight mass spectrometry of polymers. The selection of an appropriate MALDI matrix, cationization salt and sample preparation techniques are critical success factors for obtaining a reliable mass spectrum and to infer structural information such as monomer mass(es) and end-groups. However even under optimized conditions mass discrimination in the analysis of polydisperse polymers and specific oligomer discrimination might occur. Hence hyphenated techniques such as size exclusion chromatography (SEC)/MALDI have been developed. Many different polymer applications appeared in recent literature, but most studies deal with homopolymers. Many challenges remain, particularly in the fields of halogenated polymers, polyolefines, copolymers, blends, and in the sequencing of block-copolymers. © 1999 John Wiley & Sons, Inc., Mass Spec Rev 18: 309–344, 1999

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Maldi time-of-flight mass spectrometry of synthetic polymers

The chemistry of side reactions and byproduct formation in the system NMMO/cellulose (Lyocell process)

Publisher Summary This chapter presents a discussion on the coordination chemistry of 2,2’: 6’, 2”-terpyridine and higher oligopyridines. The potentially terdentate ligand 2,2’: 6’, 2”-terpyridine presented, was first isolated by Morgan and Burstall as one of the numerous products from the reaction of pyridine with iron (III) chloride. There has been a considerable increase in the use of these ligands in recent years, prompted in part by the attractive photochemical and photophysical properties exhibited by complexes of the related ligands 2,2’-bipyridine and 1,10-phenanthroline. The chapter discusses stabilization of unusual complexes and states that low oxidation states are characterized by an excess of electron density at the metal atom; stabilization may be achieved by the use of ligands capable of reducing that electron density. One of the simplest ways to reduce the electron density is to design ligands with low-lying vacant orbitals of suitable symmetry for overlap with filled metal orbitals. This results in the transfer of electron density from the metal to the ligand (back-donation). In general, ligand nonbonding or π antibonding orbitals are of the correct symmetry for such overlap. The oligopyridines are ideally suited to such roles; they possess a filled highest occupied molecular orbital (HOMO) and a vacant lowest unoccupied molecular orbital (LUMO) of suitable energies for interaction with metal d orbitals. The chapter also discusses monodentate, bidentate, and bridging; terdentate and higher polydentate; cyclometallated, and others.

The Coordination Chemistry of 2,2′:6′,2″-Terpyridine and Higher Oligopyridines

Stepwise Assembly of Amphiphilic Ruthenium Sensitizers and their Applications in Dye Sensitized Solar Cell

Efficient stabilization of cellulose solutions in NMMO(1) against side reactions and their harmful effects meansprevention of both homolytic and heterolytic side reactions, which is mainlyaccomplished by trapping radicals, formaldehyde, andN-(methylene)iminium ions (5). Whileradical trapping is commonly reflected by the antioxidativeefficiency, the effectivity against heterolyticdegradationin the Lyocell dope can be expressed by the newly introduced term‘formaldehyde trapping capacity’ (FTC). Propyl gallate (PG,4), the most widely applied Lyocell stabilizer nowadays, actsas a phenolic antioxidant, and is finally oxidized to a deeply colored, highlyconjugated chromophore (11) via ellagicacid (10). It was demonstrated that 4 is alsoa quencher of formaldehyde and N-(methylene)iminium ions,both in organic solutions of NMMO and in Lyocell dope. The processes of radicaltrapping and scavenging of HCHO/5 are competitive in the caseof propyl gallate. A novel oxa-chromanol derivative, PBD (14),was designed as stabilizer for Lyocell solutions. In analogy to propyl gallate,PBD acts as a scavenger of all three dangerous species, namely HCHO,5 and radicals. Upon oxidation by radical species, PBDreleasesacetaldehyde which acts as a very efficient HCHO trap. Thus, in contrast topropyl gallate, radical trapping and HCHO trapping are not competitive. Boththeantioxidative efficiency and the capacity to trap HCHO and 5are higher for PBD as compared to propyl gallate. In preliminary stabilizertesting, mixtures of PBD and PG proved to be especially effective.

Cellulose solutions in N-methylmorpholine-N-oxide (NMMO) – degradation processes and stabilizers

New decarbonylation reactions of carbonylruthenium(II) complexes

Constituents of Some Species of Beilschmiedia and Endiandra (Lauraceae) : New Endiandric Acid and Benzopyran Derivatives Isolated from B. oligandra.

Selective monodecarbonylation of Ru(CO)2X2L2 complexes

4,6-Dimethoxy-2,3-diphenylindole undergoes quinone oxidation to give the corresponding 7,7′-bi-indolyl derivative in high yield.

D. St. C. Black

Papers

New decarbonylation reactions of carbonylruthenium(II) complexes

Constituents of Some Species of Beilschmiedia and Endiandra (Lauraceae) : New Endiandric Acid and Benzopyran Derivatives Isolated from B. oligandra.

Selective monodecarbonylation of Ru(CO)2X2L2 complexes

Formation of 7,7'-bi-indolyls by oxidative dimerization of 4,6-dimethoxy-2,3-diphenylindole

Fragmentation Observed in Continuous Extraction Linear MALDI: a Cautionary Note