Synthesis, physicochemical and optical properties of bis-thiosemicarbazone functionalized graphene oxide

Article abstract of DOI:10.1016/j.saa.2017.06.045

Fluorescent materials are important for low-cost opto-electronic and biomedical sensor devices. In this study we present the synthesis and characterization of graphene modified with bis-thiosemicarbazone (BTS). This new material was characterized using Fo

Full text of DOI:10.1016/j.saa.2017.06.045

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Synthesis, physicochemical and optical properties of bis-
thiosemicarbazone functionalized graphene oxide
Santosh Kumar, Mohmmad Y. Wani, Claudia T. Arranja, Ricardo
A.E. Castro, José A. Paixão, Abilio J.F.N. Sobral
PII:
DOI:
Reference:
S1386-1425(17)30523-1
doi: 10.1016/j.saa.2017.06.045
SAA 15261
Spectrochimica Acta Part A: Molecular and Biomolecular
Spectroscopy
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Revised date:
Accepted date:
7 November 2016
13 June 2017
30 June 2017
Please cite this article as: Santosh Kumar, Mohmmad Y. Wani, Claudia T. Arranja, Ricardo
A.E. Castro, José A. Paixão, Abilio J.F.N. Sobral , Synthesis, physicochemical and optical
properties of bis-thiosemicarbazone functionalized graphene oxide, Spectrochimica Acta
Part A: Molecular and Biomolecular Spectroscopy (2017), doi: 10.1016/j.saa.2017.06.045
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Synthesis, physicochemical and optical properties of bis-thiosemicarbazone
functionalized graphene oxide
Santosh Kumar*,1, Mohmmad Y. Wani1,†, Claudia T. Arranja1, Ricardo A. E. Castro2, José A.
Paixão3, and Abilio J. F. N. Sobral*,1
1Department of Chemistry, University of Coimbra, P-3004-535 Coimbra, Portugal
2CEF, Faculty of Pharmacy, University of Coimbra, P-3000-548 Coimbra, Portugal
3Department of Physics, University of Coimbra, P-3004-516 Coimbra, Portugal
ABSTRACT
Fluorescent materials are important for low-cost opto-electronic and biomedical sensor devices.
In this study we present the synthesis and characterization of graphene modified with bis-
thiosemicarbazone (BTS). This new material was characterized using Fourier transform infrared
spectroscopy (FT-IR), Ultraviolet-visible (UV-vis) and Raman spectroscopy techniques. Further
evaluation by X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), differential scanning
calorimetry (DSC), scanning electron microscopy (SEM) and atomic-force microscopy (AFM)
allowed us to fully characterize the morphology of the fabricated material. The average height of
the BTSGO sheet is around 10 nm. Optical properties of BTSGO evaluated by
photoluminescence (PL) spectroscopy showed red shift at different excitation wavelength
compared to graphene oxide or bisthiosemicarbazide alone. These results strongly suggest that
BTSGO material could find potential applications in graphene based optoelectronic devices.
KEYWORDS: Graphene oxide; Bis-thiosemicarbazone; Characterization; Photoluminescence.
*Corresponding author. Tel.: +351 239854476; Fax: +351 239827703; E-mail:
santoshics@gmail.com (Santosh Kumar); asobral@ci.uc.pt (Abilio J. F. N. Sobral)
1

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†Present Address: Texas Therapeutics Institute, Brown Foundation Institute of Molecular
Medicine, The University of Texas Health Science Center at Houston, 1881 East Road, Houston,
77054, Texas, United States.
1. Introduction
In recent decades, graphene oxide has taken on an assortment of diverse roles, not only in
optoelectronics but also as a material for nanoscale engineering. Graphene oxide, as a graphene-
based inorganic carbon material, possesses many exceptional properties including nanoscale
controllability and biocompatibility which merit attention for many potential applications. As a
robust yet flexible material it provides many possibilities for facile modification and fabrication
to produce other desired graphene based materials [1-7]. Recently, graphene has advanced its
applications in biomedical and energy engineering [8-10]. Also the improvement of graphene
based fluorescent sensors for evaluating biomolecules has received great attention due to in situ
cellular imaging studies [11]. In a recent study of chitosan/graphene oxide nanocomposite, it was
found that the pH conditions affect the interaction between polymer and graphene oxide and
hence the optical properties of the material [12]. Since graphene is a zero-bandgap
semiconductor the possibility of observing luminescence is highly unlikely [13], and therefore,
studies being conducted to increasing the band gap are important. An important strategy is to
combine graphene oxide with some conjugated organic molecule to improve its optical
properties.
Thiosemicarbazones constitute an interesting class of compounds with wide pharmacological
versatility with anti-tumor, anti-cancer, anti-inflammatory, anti-protozoal, anti-bacterial and anti-
viral activities [14-19]. Due to the presence of a conjugated system of double bonds and
heteroatoms in the bis-thiosemicarbazone skeleton, it was speculated that the conjugation or
2

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fabrication of bis-thiosemicarbazone with graphene oxide could enhance the optical properties of
graphene oxide. Despite the large amount of work done on graphene oxide, no literature
precedents were found describing the fabrication and the study of the optical properties of bis-
thiosemicarbazone-graphene oxide materials. We herein report the synthesis, physico-chemical
and optical properties of BTSGO, a new material with potential to be applied as optical sensor or
biosensor.
2. Experimental section
2.1. Materials and reagents
Graphite, 30% H2O2, KMnO4, benzene-1,4-dicarbaldehyde and thiosemicarbazide were
purchased from Sigma-Aldrich Co., (USA). Hydrochloric acid, SOCl2 and H2SO4 was obtained
from Merck (Germany) and were used without further purification.
2.2. Synthesis of Bis-thiosemicarbazone (BTS) (3).
Bis-thiosemicarbazone (BTS) was synthesized as outlined in Scheme 1. Benzene-1,4-
dicarbaldehyde (1) (1 mmol, 0.13 g) was mixed with thiosemicarbazide (2) (2 mmol, 0.18 g) in
ethanol with few drops of 10% NaOH, and placed in reflux for 5 h. Completion of the reaction
was monitored by thin layer chromatography (TLC). After completion of the reaction, a pale
yellow precipitate of BTS (3) was formed, which was filtered, dried and recrystallized in
dichloromethane.
Yield 85%; IR νmaxcm-1: 3396 (NH), 3264, 3191 (NH2), 3010 (C-H), 1589 (C = C), 1515 (C =
1
N), 1279 (C–N), 1120 (C = S); H NMR (DMSO-d6) (ppm): 8.30 (2H, s, -NH), 8.00 (2H, s,-
3