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Crystallography 2018 Structural Chemistry & Crystallography Communication
ISSN: 2470-9905 Page 24
June 04-05, 2018
London, UK
3rd Edition of International Conference on
Advanced Spectroscopy,
Crystallography and Applications
in Modern Chemistry
Poly((2,5-bis(1-methylpyrrol-2-yl)thiophene)squaraine) can
be synthesized as a dark green insoluble powder which
when subjected to shear force and pressed as a disk exhibits
a gold-green near optical quality surface with semi-metallic
behaviour. Reflectivity measurements at a wavelength of 819
nm reveal a high (72°) pseudo-Brewster angle and non-zero
p-reflectivity whilst electrical measurements using a four-point
probe return a conductivity of 1 x 10-5 -1. Unexpectedly
the disks also exhibit magneto-optic (MO) activity which it
appears must arise from a weak magnetic component intrinsic
to the samples. In both the longitudinal and transverse Kerr
configurations large fractional changes in reflectivity (∆I/I
≈ 2.5x 10-2) are observed across a wide range of angles of
incidence for wavelengths between 400 nm and 1064 nm on
application and reversal of a magnetic field. Anomalously for
these configurations all the MO effects observed are quadratic
in the applied field and no first-order effects linear in applied
field are observed for any state of incident polarisation.
Examined using conventional magnetometry disk samples
return saturation magnetization values of 4.13 x 10-3 emu.g-1
on a vibrating sample magnetometer and smaller samples
similarly processed and prepared for examination by Squid
magnetometer confirmatory values of 4.9 x10-3 emu.g-1.
Magnetization curves from both instruments have a similar
form saturating at about 1.14 kOe and are also in close
correspondence with curves derived by plotting the magneto-
optic signal as a function of field. Similarly both the magnetic
and magneto-optic behaviour of all samples is isotropic in
plane.All experimental observations on this polymer appear
to be commensurate with the development of some form of
magnetic state throughout very limited regions of the material.
A model able to reconcile the magnetic and MO observations
is presented as well as a discussion of the importance of the
material structure in relation to the observed phenomenon.
Recent Publications
1. Lynch DE, Hamilton DG (2018) Microreview: Pyrrol-3-yl
squaraines (including indol-3-yl squaraines). Journal
of Heterocyclic Chemistry DOI: 10.1002/jhet.3173.
2. Lynch DE, Hamilton DG (2017) Croconaine Dyes –
the Lesser Known Siblings of Squaraines. European
Journal of Organic Chemistry 3897-3911.
3. Lynch DE, Hamilton DG (2017) The History of Azulenyl
Squaraines. Australian Journal of Chemistry 70:857-
871.
4. Lynch DE (2015) Pyrrolyl Squaraines – Fifty Golden
Years. Metals 5: 1349-1370.
5. Lynch DE, Newman DM, Wears ML, Matelon RJ (2013)
Novel magneto-optic behavior from a polysquaraine.
Synthetic Metals 171:15-22.
Biography
Daniel Lynch is a materials chemist and crystallographer with recent experi-
ence in plastics additives; BAppSc degree (1990) and PhD (1994), fromQUT
in Brisbane (Australia). A postdoctoral fellowship at Cranfield University (UK)
preceded a six-year university research fellowship at Coventry University
(UK), becoming a Senior Lecturer in 2001 and a Reader of Applied Chem-
istry in 2007 at the same institution. He is the author of 250 research publi-
cations, the principal inventor of Exilica’s patented technology and became
the full-time Technical Director of Exilica Limited in 2007, a post that he had
held on a part-time basis since Exilica’s incorporation in May 2005. (orcid.
org/0000-0001-6210-5316).
NOVEL MAGNETO-OPTIC BEHAVIOR FROM A POLYSQUARAINE: STRUCTURE
/ PROPERTY RELATIONSHIP
Daniel E. Lynch
Exilica Limited, Coventry, UK
Daniel E. Lynch, Struct Chem Crystallogr Commun 2018, Volume 4
DOI: 10.21767/2470-9905-C1-005