Research topics in the Constable/Housecroft Group


Light harvesting using inorganic coordination complexes as dyes in dye-sensitized solar cells (DSCs)

We are focusing on the development of dyes (sensitizers) for attachment to n-type semiconductors (usually TiO2) for incorporation into DSCs. The now well-established Grätzel-type DSCs use ruthenium(II)-containing dyes, and our research thrust is the development of dyes that contain first row d-block metals (e.g. copper, zinc) which are Earth abundant. The major challenge is to increase the sunlight-to-electrical-power conversion efficiencies of the dyes.


For an overview of this area:

'Light harvesting with Earth abundant d-block metals: towards a sustainable materials chemistry' B. Bozic-Weber, E. C. Constable and C. E. Housecroft, Coord. Chem. Rev., 2013, 257, 3089-3106.



Development of emissive complexes for application in light-emitting electrochemical cells (LECs)

Tuning the photoluminescence (PL) properties of iridium(III) complexes of the type [Ir(N^N)(C^N)2]+ where N^N is a chelating ligand such as a 2,2'-bipyridine derivative and C^N is a cyclometalling chelate, can be achieved by careful selection and combination of the ligands. Colour tuning is one goal; another is extending the lifetimes and increasing the quantum yields of the emissions. For applications in light-emitting electrochemical cells, we must also investigate the electroluminescent properties under device configuration - this work is carried out in collaboration with the research groups of Dr Henk Bolink and Professor Enrique Ortí (University of Valencia).


For insight into this area:

'Tuning the photophysical properties of cationic iridium(III) complexes containing cyclometallated 1-(2,4-difluorophenyl)-1H-pyrazole through functionalized 2,2'-bipyridine ligands: blue but not blue enough'
E. Baranoff, H. J. Bolink, E. C. Constable, M. Delgado, D. Häussinger, C. E. Housecroft, M. K. Nazeeruddin, M. Neuburger, E. Ortí, G. E. Schneider, D. Tordera, R. M. Walliser and J. A. Zampese, Dalton Trans., 2013, 42, 1073-1087.

Efficient Green Light-Emitting Electrochemical Cells Based on a Sulfone Substituent on the Cyclometalating Ligands
D. Tordera, A. M. Bünzli, A. Pertegás, J. M. Junquera-Hernández, E. C. Constable, J. A. Zampese, C. E. Housecroft, E. Ortí and H. J. Bolink, Chem. Eur. J, 2013, 19, 8597-8609.

Green-emitting iridium(III) complexes containing sulfone-functionalized cyclometallating 2-phenylpyridine ligands
E. C. Constable, C. D. Ertl, C. E. Housecroft and J. A. Zampese, Dalton Trans., 2014, 43, 5343-5356.



Water splitting and water oxidation catalysts

Water splitting is the conversion of liquid water to H2 and O2 using visible light energy. Nature achieves this by photosynthesis, and in biological processes, a highly organized phospholipid membrane is crucially important. One of our on-going areas of research is the development of water splitting (to form H2 and O2 from H2O) or water oxidation (looking only at one half of the water splitting process) catalysts. One approach is to use Langmuir-Blodgett (LB) films to transfer ordered monolayers of both a polyoxometallate cluster and the bis- or tris(bipyridine) ruthenium(II) photosensitizer onto a conducting substrate for use in a water splitting device.


For relevant work:

Bis(4'-(4-pyridyl)-2,2':6',2"-terpyridine)ruthenium(II) complexes and their N-alkylated derivatives in catalytic light-driven water oxidation
H. Lv, J. A. Rudd, P. F. Zhuk, J. Y. Lee, E. C. Constable, C. E. Housecroft, C. L. Hill, D. G. Musaev and Y. V. Geletii, RSC Advances, 2013, 3, 20647-20654.

Assembling model tris(bipyridine)ruthenium(II) photosensitizers into ordered monolayers in the presence of the polyoxometallate anion [Co 4(H2O)2 (α-PW9O34)2]10-
N. S. Murray, J. A. Rudd, A.-C. Chamayou, E. C. Constable, C. E. Housecroft, M. Neuburger and J. A. Zampese, RSC Advances, 2014, 4, 11766-11775.



Functional coordination polymers and networks

The combination of transition metal-based building blocks with polypyridyl ligands such as 4,2':6',4''-terpyridine is a powerful strategy for the assembly of 1D-, 2D and 3D polymers and networks. Gaining control over the assembly processes is challenging. Ligand backbones may be functionalized with, for example, photoactive domains. Our interests in these systems are both understanding their structural characteristics (challenging crystallography) and developing functionalized systems that can act as, e.g. sensors or host materials.


For a review of recent advances in the area:

C. E. Housecroft, Dalton Trans., 2014, 43, 6594 - 6604.

For insight into the use of ditopic ligands:

2D ➝ 2D Parallel interpenetration of (4,4) sheets constructed from a ditopic bis(4,2':6',4''-terpyridine)
E. C. Constable, C. E. Housecroft, S. Vujovic and J. A. Zampese, CrystEngComm, 2014, 16, 3494-3497.