XIV
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International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
340
T9: P–14
Signaling mechanism for a new Zn(II) turn-on fluorescent probe
– a computational study
Mercedes Kukułka
1
, Mariusz P. Mitoraj
1
, and Monika Srebro-Hooper
1
1
Department of Theoretical Chemistry, Faculty of Chemistry, Jagiellonian University, R. Ingardena
3, 30 060 Krakow, Poland, e-mail: kukulka@chemia.uj,edu.pl
In recent years, emission chemosensors have attracted a great deal of attention for detecting
various (bio)chemical analytes because of their simplicity, high sensitivity, and real-time
monitoring with fast response. In particular, there is a high demand for development of novel
fluorescent probes for selective sensing of biologically relevant transition-metal ions, such as,
among others, Cd(II), Hg(II), and Zn(II), due to their potential environmental and biological
applications [1–2].
Up to now, a number of fluorescence-based sensors have been reported. Among these,
several chemical pathways which control their photophysical properties have been described.
The most explored signaling mechanisms include photo-induced electron transfer (PET),
chelation-enhanced fluorescence (CHEF), intramolecular charge transfer (ICT), metal-ligand
charge transfer (MLCT), and fluorescence resonance energy transfer (FRET). Aggregation-
induced emission (AIE), C=N isomerization, and excited-state intramolecular proton transfer
(ESIPT) have also recently been reported [3–5]. Nevertheless, assigning a proper mechanism for
a particular system is not a straightforward task, especially that they may coincide. Here, the
importance of quantum-chemical calculations cannot be understated as they enable a meaningful
interpretation of experimental data and thus appear to be indispensable in understanding of
sensing mechanism.
In the present work results of combined experimental and theoretical research on a newly
proposed chemosensor for selective detection of Zn(II) will be presented from the (TD-)DFT
perspective. Photophysical properties of the naphthylmethylene-hydrazine-based probe and the
metal complex (Figure 1) along with the predicted signaling mechanism will be reported.
Possible aggregation-induced emission for the ligand in the presence of water will be
investigated.
Fig. 1. Complexation / decomplexation process of Zn(II) with naphthylmethylene-hydrazine-based probe.
Keywords: fluorescence; chemosensors; first-principles calculations
Acknowledgment
The research was supported by PLGrid Infrastructure.
References
[1] Y. Jeong, J. Yoon, Inorg. Chim. Acta, (2012) 2.
[2] Y. Hu, Q. Li, H. Li, Q. Guo, Y. Lu, Z. Li, Dalton Trans. (2010) 11344.
[3] J. Wu, W. Liu, J. Ge, H. Zhang, P. Wang, Chem. Soc. Rev. (2011) 3483.
[4] A. T. Afaneh, G. Schreckenbach, J. Phys. Chem. (2015) 8106.
[5] A. P. de Silva, H. Q. N. Gunaratne, T. Gunnlaugsson, A. J. M. Huxley, C. P. McCoy, J. T.
Rademacher, T. E. Rice, Chem. Rev. (1997) 1515.
XIV
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International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
341
T9: P–15
Ab initio multi-reference perturbation theory study on the uranium
monocarbide UC molecule including the spin-orbit coupling
Maksim Shundalau
1,2
, Darya Meniailava
1
1
Physics Department, Belarusian State University, 4 Nezaležnaści Ave., 220030, Minsk, Belarus,
e-mail: shundalov@bsu.by
2
A.N. Sevchenko Institute of Applied Physical Problems at Belarusian State University, 7 Kurčataǔ
Str., 220108, Minsk, Belarus
Uranium carbides, which have several stoichiometric modifications (uranium monocarbide
UC, uranium dicarbide UC
2
, etc.), are considered as perspective materials for nuclear energetics.
The electronic states of the UC molecule were studied theoretically in [1–3] at DFT and
CASPT2 levels of theory. The energies of the vertical excitations for the several low-lying
electronic states and some molecular spectroscopic constants were obtained.
In this work we have calculated the potential energy curves (PECs) for the ground and some
low-lying excited states of the UC molecule at the multi-reference CASSCF/XMCQDPT2 level
of theory including the spin-orbit coupling (SOC). We have predicted the molecular
spectroscopic constants and other characteristics for the vibronic states. The ab initio calculation
of the electronic structure of an actinide-containing molecular system is a non-trivial task that
requires taking into account the relativistic effects, the static and dynamic components of the
correlation energy, a large number of excited configurations, etc. The Stuttgart relativistic
ECP80 for uranium atom and TZ-basis sets for uranium and carbon atoms have been used in our
calculations. The active space for the CASSCF calculations was 8 electrons in 10 orbitals. The
CASSCF calculations were realized for low-lying quintet (S = 2) and septet (S = 3) states. These
calculations were performed pointwisely for the internuclear distances ranging 1.70–20.00 Å.
Then the calculations for quintet and septet states were performed in the XMCQDPT2
(Extended Multi-Configuration Quasi-Degenerate 2
nd
Order Perturbation Theory) [4]
approximation. Finally, the SOC calculations were performed with the Pauli–Breit operator.
As there is no experimental values of spectroscopic parameters for ground and excited states
of the UC molecule to determine the accuracy of the calculations we compare the calculated
energies of molecular states at the dissociation limits (at the internuclear distance of 20.0 Å)
with the sum of the experimental energies [5] of separated uranium and carbon atoms. The
calculated values (26.3, 43.6 and 620.9 cm
–1
) are in a good agreement with the NIST [5]
experimental data (16.4, 43.4 and 620.3 cm
–1
). This fact can be a criterion pointing to the
adequacy of the determined spectroscopic parameters for the ground and excited electronic
states of the uranium monocarbide molecule. For example, for the ground state (Ω = 1) we
obtained the equilibrium internuclear distance Re = 2.12 Å and dissociation energy De = 28152
cm
–1
.
Keywords: uranium monocarbide; vibronic states; ab initio; multi-reference perturbation theory
Acknowledgment
This work is supported by the MOST foundation (EU funded project for enhancing professional contacts
between Belarus and the EU).
References
[1] X. Wang, L. Andrews, P.-Å. Malmqvist, B.O. Roos, A.P. Gonçalves, C.C.L. Pereira, J. Marçalo, C.
Godart, B. Villeroy, J. Am. Chem. Soc. 132 (2010) 8484.
[2] X. Wang, L. Andrews, D. Ma, L. Gagliardi, A.P. Gonçalves, C.C.L. Pereira, J. Marçalo, C. Godart, B.
Villeroy, J. Chem. Phys. 134 (2011) 244313.
[3] P. Pogány, A. Kovács, L. Visscher, R.J.M. Konings, J. Chem. Phys. 145 (2016) 244310.
[4] A.A. Granovsky, J. Chem. Phys. 134 (2011) 214113.
[5] NIST Atomic Spectra Database.
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