Sir Joseph Swan Centre for Energy Research

Staff Profile

Emeritus Professor Anthony Harriman

Emeritus Professor

Background

Background

Despite 50 years of continuous experimental work and in excess of 400 publications, there are still many areas of applied molecular photophysics that attract deep interest. In fact, the two research topics that were my introduction to the field, namely the development of photodegradable plastics and artificial photosynthesis, remain unsolved and as significant as ever. In part, progress in these areas is hindered by a desire to understand mechanisms, probabilities and reaction rates at the expense of producing a workable solution. This is certainly true in my case, although patents have been issued for an artificial photosynthetic device (with Lord George Porter), effective photobleaches that operate at low temperature (with the Procter & Gamble Co.), and pressure-sensitive anti-counterfeit systems (with the Bank of England). The real interest, however, lies with identifying intermediate species in photochemical processes, especially those related to natural photosynthesis, and in manipulating environmental effects to engineer high levels of photo-selectively.

No longer involved in undergraduate teaching, pedagogical matters take the form of writing a monograph on Colligative Properties, with lots of example calculations. There is also time to learn how to apply matrix theory and phasor methods for better representing multi-component photophysical processes. A book on Artificial Light-Harvesting Networks is slowly taking shape. I am actively involved in Advisory Boards, Editorial Boards and Review Boards.

The Annual Daedalus Lecture is organised jointly with Prod Bernard Golding and recognises the outstanding contributions to the public awareness of science made by Dr. David Jones. The lecture is intended for an interactive audience and is on-hold until restrictions imposed by COVID-19 have eased. The two previous lectures were given by Sir Martyn Poliakoff and Prof. David Leigh. Details for the next lecture will be announced once the situation has stabilised.

Please note that I am not taking any new students or postdoctoral associates into my research group. Suggestions for potential collaborations are always welcome.

Qualifications

PhD
Grad RIC
HNC
ONC

Previous Positions

SRC Postdoctoral Fellow, The Royal Institution, London, U.K. 1974-75
EEC Postdoctoral Fellow, The Royal Institution, London, U.K. 1975-77
Dewar Research Fellow, The Royal Institution, London, U.K. 1977-88
Assistant Director, The Royal Institution, London, U.K. 1980-88
Visiting Scientist, National Bureau of Standards, Washington, D.C., U.S.A. 1985-86
Deputy Director, Center for Fast Kinetics Research, Austin, Texas, U.S.A. 1988-89
Director, Center for Fast Kinetics Research, Austin, Texas, U.S.A. 1989-94
Professor of Physical Chemistry, University of Texas, Austin, Texas, U.S.A. 1989-93
Professeur Invité, Université Louis Pasteur, Strasbourg, France 1993
Professeur Invité, School of Chemistry, E.H.I.C.S., Strasbourg, France 1994
Visiting Professor, Tokyo Metropolitan University, Tokyo, Japan 1995
Professeur, Université Louis Pasteur, Strasbourg, France 1995-99
Professor of Physical Chemistry, University of Newcastle, U.K. 1999-2019

Professor Emeritus, Newcastle University, U.K. 2019-

Honours and Awards

Sir James Dewar Research Fellowship 1977
Royal Society (London) Visiting Research Scholarship 1982
Corday-Morgan Medal (RSC) 1984
Le Prix Grammaticakis-Neumann en Photochimie 1985

RSC Chemical Dynamics Award 2011

Newcastle University Best Teacher Award 2016

UK Solar Fuels Lifetime Achievement Award 2018


Research

Research interests

The primary purpose behind the search for reaction mechanisms is to identify means by which to control, optimise and manipulate photochemical processes, with the ultimate ambition being to replace key reagents with improved prototypes. This chain of events can be illustrated by our recent work relating to stochastic super-resolution microscopy, where the dominant fluorescent species is a cyanine dye. We have developed an analytical protocol for measuring fluorescence probability at long wavelength (Pub. 11) and examined the role of competing photo-isomerisation with a well-known cyanine-conjugate (Pub. 7). On-going work, in collaboration with Aliaksandra Lisouskaya, is aimed at characterising spectroscopic and kinetic parameters for radicals derived from cyanine dyes of different conjugation length. A similar approach has been taken with singlet exciton fission occurring with TIPS-pentacene. The photophysical properties have been determined for the parent compound in dilute solution (Pub. 4) and, together with Tetsuro Majima, we have pioneered the use of pulse radiolysis to measure rates and yields of singlet fission in a related bichromophore (Pub. 10). A collaboration with Luis Arnaut has resulted in the first application of photoacoustic calorimetry to measure the triplet excitation energy of TIPS-pentacene and the bichromophore (Pub. 2). On-going research is aimed at resolving NIR phosphorescence from linear poly-acenes.

Concentration quenching is a long-standing problem in the field of molecular photophysics and was first explored in detail with solutions of chlorophyll. Covalently-linked bichromophores also exhibit fluorescence quenching due to the proximity effect and, in many cases, display pronounced excitonic coupling between the chromophores. These effects hinder the development of artificial light-harvesting arrays where high chromophore densities are critical. The degree of excitonic coupling can be controlled by careful attention to the mutual orientation of the respective transition dipole moment vectors. For example, in a collaboration with Raymond Ziessel, we found that these vectors are parallel, anti-parallel and obtuse, respectively, for the ortho-, para- and meta-bridged set of bis-boranils illustrated here. The para derivative is strongly fluorescent and does not show the strong polarity dependence observed for the mono-boranil complex. Similar protocols can be applied to crystalline samples where close proximity does not necessarily preclude emission. For example, the “half-BOPHY” species synthesized by Özgür Altan Bozdemir, is strongly fluorescent in the crystalline state but very weakly emissive in solution. Here, the difference relates to mobility of the transferrable proton. The detailed exploration of the luminescence properties of photonic crystals is an exciting new development in the field that could lead to the discovery of novel materials with unprecedented applications.

 

Selected recent publications

1) Algoazy, N., Knight, J.G., Waddell, P.G., Aerts, R., Herrebout, W., Al-Sharif, H.H.T., Karlsson, J.K.G., Harriman, A. Synthesis, Structure and Photophysical Properties of a New Class of Inherently Chiral Boron(III) Chelates—The tert-Leucine Complexes. (2021) Chemistry - A European Journal, 27 (16), pp. 5246-5258. DOI: 10.1002/chem.202005246

2) Karlsson, J.K.G., Atahan, A., Harriman, A., Tkachenko, N.V., Ward, A.D., Schaberle, F.A., Serpa, C., Arnaut, L.G. Singlet Exciton Fission and Associated Enthalpy Changes with a Covalently Linked Bichromophore  Comprising TIPS-Pentacenes Held in an Open Conformation. (2021) Journal of Physical Chemistry A, In press. DOI: 10.1021/acs.jpca.0c09961

3) Harriman, A., Bozdemir, Ö.A., Gultekin, D.D. Triplet distribution in a symmetrical zinc (II) porphyrin-BODIPY pentameric array. (2020) Journal of Physical Chemistry A, 124 (51), pp. 10736-10747. DOI: 10.1021/acs.jpca.0c09243

4) Schaberle, F.A., Serpa, C.; Arnaut, L.G., Ward, A.D., Karlsson, J.K.G., Atahan, A., Harriman, A. The Photophysical Properties of Triisopropylsilyl-ethynylpentacene—A Molecule with an Unusually Large Singlet-Triplet Energy Gap—In Solution and Solid Phases. (2020) Chemistry2 (2), pp. 545-564. DOI: org/10.3390/chemistry2020033

5) Al-Sharif, H.H.T., Ziessel, R., Waddell, P.G., Dixon, C., Harriman, A. Origin of Fluorescence from Boranils in the Crystalline Phase. (2020) J. Phys. Chem. A, 124 (11), pp. 2160–2172 DOI: 10.1021/acs.jpca.0c00905

6) Bozdemir, Ö.A., Al-Sharif, H.H.T., McFarlane, W., Waddell, P.G., Benniston, A.C., Harriman, A. Solid-State Emission from Mono- and Bichromophoric Boron Dipyrromethene (BODIPY) Derivatives and Comparison with Fluid Solution. (2019) Chemistry - A European Journal, 25 (68), pp. 15634-15645. DOI: 10.1002/chem.201903902

7) Karlsson, J.K.G., Laude, A., Hall, M.J., Harriman, A. Photo-isomerization of the Cyanine Dye Alexa-Fluor 647 (AF-647) in the Context of dSTORM Super-Resolution Microscopy. (2019) Chemistry - A European Journal, 25 (65), pp. 14983-14998. DOI: 10.1002/chem.201904117

8) Woodford, O.J., Ziessel, R., Harriman, A., Wills, C., Alsimaree, A.A., Knight, J.G. Optical spectroscopic properties recorded for simple BOPHY dyes in condensed media: The mirror-symmetry factor. (2019) Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 208, pp. 57-64. DOI: 10.1016/j.saa.2018.09.047

9) Woodford, O.J., Ziessel, R., Harriman, A. Photofading of an Extended BOPHY Chromophore Dispersed in Poly(methyl methacrylate) as a Chemical Actinometer. (2018) ChemPhotoChem, 2 (12), pp. 1046-1054. DOI: 10.1002/cptc.201800130

10) Karlsson, J.K.G., Atahan, A., Harriman, A., Tojo, S., Fujitsuka, M., Majima, T. Pulse Radiolysis of TIPS-Pentacene and a Fluorene-bridged Bis(pentacene): Evidence for Intramolecular Singlet-Exciton Fission. (2018) Journal of Physical Chemistry Letters, 9 (14), pp. 3934-3938. DOI: 10.1021/acs.jpclett.8b02006

11) Karlsson, J.K.G., Woodford, O.J., Mustroph, H., Harriman, A. Cyanine dyes as ratiometric fluorescence standards for the far-red spectral region. (2018) Photochemical and Photobiological Sciences, 17 (1), pp. 99-106. DOI: 10.1039/c7pp00333a

12) Harriman, A. Electrochemical catalysts to meet the challenge for sustainable fuel production from renewable energy. (2021) Current Opinion in Green and Sustainable Chemistry, in press. https://authors.elsevier.com/sd/article/S2452-2236(21)00048-1

13) Al-Sharif, H.H.T., Harriman, A. Bio-inspired artificial light-harvesting arrays based on boron(III)-chelates. (2021) Recent Advances in Boron-Containing Materials. IntechOpen. DOI: 10.5772/intechopen.91853

 

Teaching

No longer involved in undergraduate teaching, pedagogical matters take the form of writing a monograph on Colligative Properties, with lots of example calculations. There is also time to learn how to apply matrix theory and phasor methods for better representing multi-component photophysical processes. A book on Artificial Light-Harvesting Networks is slowly taking shape. I am actively involved in Advisory Boards, Editorial Boards and Review Boards.


Publications