Andrew Beeby

Bio: Andrew Beeby is an academic researcher from Durham University. The author has contributed to research in topics: Excited state & Luminescence. The author has an hindex of 50, co-authored 178 publications receiving 8935 citations.

Non-radiative deactivation of the excited states of europium, terbium and ytterbium complexes by proximate energy-matched OH, NH and CH oscillators: an improved luminescence method for establishing solution hydration states

Abstract: The radiative rate constants for depopulation of the excited states of closely-related series of anionic, neutral and cationic europium, terbium and ytterbium complexes have been measured in H2O and D2O. With the aid of selective ligand deuteriation, the relative contributions of OH, NH (both amide and amine) and CH oscillators have been measured and critically assessed. Quenching of the Eu 5D0 excited state by amine NH oscillators is more than twice as efficient as OH quenching. The importance of the distance between the excited Ln ion and the XH oscillator is described with recourse to published crystallographic information. The general equation, q = A′(ΔkH2O–kD2O)corr is presented and revised values of A′ for Eu (1.2 ms), Tb (5 ms) and Yb (1 µs) given, which allow for the quenching contribution of closely diffusing OH oscillators. The relevance of such studies to the hydration state of certain gadolinium complexes is described and clear evidence provided for a break in hydration at gadolinium.

Manipulating Charge-Transfer Character with Electron-Withdrawing Main-Group Moieties for the Color Tuning of Iridium Electrophosphors†

Abstract: A new and synthetically versatile strategy has been developed for the phosphorescence color tuning of cyclometalated iridium phosphors by simple tailoring of the phenyl ring of ppy (Hppy=2-phenylpyridine) with various main-group moieties in [Ir(ppy-X)(2)(acac)] (X=B(Mes)(2), SiPh3, GePh3, NPh2, POPh2, OPh, SPh, SO2Ph). This can be achieved by shifting the charge-transfer character from the pyridyl groups in some traditional iridium ppy-type complexes to the electron-withdrawing main-group moieties and these assignments were supported by theoretical calculations.

An Alternative Route to Highly Luminescent Platinum(II) Complexes: Cyclometalation with N∧C∧N-Coordinating Dipyridylbenzene Ligands

Abstract: The remarkable luminescence properties of the platinum(II) complex of 1,3-di(2-pyridyl)benzene, acting as a terdentate N∧C∧N-coordinating ligand cyclometalated at C2 of the benzene ring ([PtL1Cl]), have been investigated, together with those of two new 5-substituted analogues [PtL2Cl] and [PtL3Cl] {HL2 = methyl-3,5-di(2-pyridyl)benzoate; HL3 = 3,5-di(2-pyridyl)toluene}. All three complexes are intense emitters in degassed solution at 298 K (λmax 480−580 nm; φlum = 0.60, 0.58, and 0.68 in CH2Cl2), displaying highly structured emission spectra in dilute solution, with lifetimes in the microsecond range (7.2, 8.0, and 7.8 μs). On the basis of the very small Stokes shift, the highly structured profiles, and the relatively long lifetimes, the emission is attributed to an excited state of primarily 3π−π* character. At concentrations >1 × 10-5 M, structureless excimer emission centered at ca. 700 nm is observed. The X-ray crystal structure of [PtL2Cl] is also reported.

Absolute Measurements of Photoluminescence Quantum Yields of Solutions Using an Integrating Sphere

Abstract: We demonstrate that absolute measurements of the photoluminescence quantum yield of solutions can be made using an integrating sphere and a conventional fluorimeter. With this method the need for measurements against a luminescence standard is overcome. The sphere is mounted inside a commercial fluorimeter, which gives flexibility in excitation and emission wavelength ranges. A number of compounds have been investigated and the results are compared to literature values and data obtained using a comparative method.

Experimental and Theoretical Studies of the Photophysical Properties of 2- and 2,7-Functionalized Pyrene Derivatives

Abstract: Pyrene derivatives substituted at the 2- and 2,7-positions are shown to display a set of photophysical properties different from those of derivatives substituted at the 1-position. It was found tha...

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Taking advantage of luminescent lanthanide ions

Abstract: Lanthanide ions possess fascinating optical properties and their discovery, first industrial uses and present high technological applications are largely governed by their interaction with light. Lighting devices (economical luminescent lamps, light emitting diodes), television and computer displays, optical fibres, optical amplifiers, lasers, as well as responsive luminescent stains for biomedical analysis, medical diagnosis, and cell imaging rely heavily on lanthanide ions. This critical review has been tailored for a broad audience of chemists, biochemists and materials scientists; the basics of lanthanide photophysics are highlighted together with the synthetic strategies used to insert these ions into mono- and polymetallic molecular edifices. Recent advances in NIR-emitting materials, including liquid crystals, and in the control of luminescent properties in polymetallic assemblies are also presented. (210 references.)

Lanthanide luminescence for functional materials and bio-sciences

Abstract: Recent startling interest for lanthanide luminescence is stimulated by the continuously expanding need for luminescent materials meeting the stringent requirements of telecommunication, lighting, electroluminescent devices, (bio-)analytical sensors and bio-imaging set-ups. This critical review describes the latest developments in (i) the sensitization of near-infrared luminescence, (ii) “soft” luminescent materials (liquid crystals, ionic liquids, ionogels), (iii) electroluminescent materials for organic light emitting diodes, with emphasis on white light generation, and (iv) applications in luminescent bio-sensing and bio-imaging based on time-resolved detection and multiphoton excitation (500 references).