Next Article in Journal
DNA-Binding Properties of Cytotoxic Naphtindolizinedione-Carboxamides Acting as Type II Topoisomerase Inhibitors. A Combined In Silico and Experimental Study
Previous Article in Journal
Synthesis of Conjugated Polymer Based in Zn(II) Porphyrin Bearing Terminal Alkynyl Groups as Photosensitizer
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Chemistry Proceedings
Volume 3
Issue 1
10.3390/ecsoc-24-08340
chemproc-logo
Submit to this Journal
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Proceeding Paper

A New Fluorescent Calixarene Dimer: Synthesis, Optical Properties, and Sensory Applications †

by
Sérgio Costa
1,
Patrícia D. Barata
1,2,
Alexandra I. Costa
1,2 and
José V. Prata
1,2,*
1
Departamento de Engenharia Química, Instituto Superior de Engenharia de Lisboa, Instituto Politécnico de Lisboa, R. Conselheiro Emídio Navarro, 1, 1959-007 Lisboa, Portugal
2
Centro de Química-Vila Real, Universidade de Trás-os-Montes e Alto Douro, 5001-801 Vila Real, Portugal
*
Author to whom correspondence should be addressed.
†
Presented at the 24th International Electronic Conference on Synthetic Organic Chemistry, 15 November–15 December 2020; Available online: https://ecsoc-24.sciforum.net/.
Chem. Proc. 2021, 3(1), 95; https://0-doi-org.brum.beds.ac.uk/10.3390/ecsoc-24-08340
Published: 14 November 2020
(This article belongs to the Proceedings of The 24th International Electronic Conference on Synthetic Organic Chemistry)
Browse Figures
Versions Notes

Abstract

:
A new fluorogenic bis-calix[4]arene-carbazole compound (3) with an enlarged intramolecular cavity able to be involved in host–guest chemistry with large organic guests was designed. Its synthesis was accomplished for the first time using a Sonogashira–Hagihara cross-coupling reaction in the final step. The calixarene receptor was structurally characterized by FTIR and 1H/13C/2D NMR techniques and its photophysical properties evaluated. The ability of 3 to form supramolecular complexes with fullerenes (C60 and C70) was evaluated through fluorometric titration experiments. The value of the binding constants (K3:C60 = 1.39 × 105 M−1 and K3:C70= 6.88 × 104 M−1), and the free energy changes for the inclusion complexation (ΔG3:C60 = −29.33 kJ/mol and ΔG3:C70 = −27.60 kJ/mol), revealed a high sensitivity of the calixarene-carbazole host for both fullerenes. The host molecule was shown to be particularly selective towards fullerene C60.

1. Introduction

Supramolecular chemistry has stimulated the attention of the scientific community over the last few decades. Inspired by nature and exploiting the scope of non-covalent interactions such as hydrogen bonding, electrostatics, and π–π stacking, scientists have developed various synthetic systems with potential for application in different fields (e.g., smart materials, catalysts, optical sensors, complexing agents, and nanomedicine) [1,2]. In this context, several calixarene architectures, a benchmark in supramolecular chemistry [3,4], stand out as supramolecular hosts able to act as receptors for a wide range of guests (e.g., neutral and ionic molecular species). Some examples of highly sensitive and selective chemosensors for detection of explosives [5], pollutants [6], and proteins [7] based on fluorescent calixarene structures have been reported by our investigation group.
Stimulated by the increasing use of fullerene molecules in several areas, such as medical and biomedical [8] and advanced materials [9], the supramolecular chemistry of these compounds has experienced an enhancement in its research particularly in the development of selective methods for recognition in solution. Among various hosts for fullerene recognition, calix[n]arenes have played an important role since the pioneering work of Shinkai and Atwood groups [10,11]. Since calixarenes have a cavity composed of aromatic rings and fullerenes are covered by π-electrons, self-assembly through strong π–π interactions may occur between them [12]. The good compatibility between spherical (C60) or ellipsoid (C70) fullerenes and ball-shaped cavity of calixarenes to form complexes both in solution and in the solid state has been extensively investigated [13,14].
Calixarene–fullerene complexation studies in solution usually rely on NMR and/or UV–Vis measurements [15,16,17], although fluorescence spectroscopy also been used [14,18].
In this communication, we report the preliminary results regarding the synthesis, structural characterization, photophysical properties, and fluorescence-based complexation studies of a new fluorescent calixarene-3,6-carbazole dimer (3; Scheme 1) with fullerenes C60 and C70.

2. Materials and Methods

2.1. Instruments and Methods

FTIR were measured on a Bruker Vertex 70 as KBr pellets (transmission mode). The 1H/13C NMR spectra were collected on Bruker AVANCE II+ spectrometers (400 MHz); reported chemical shifts (δ/ppm) were internally referenced to CDCl3 (1H NMR, 7.26 ppm; 13C NMR, 77.16 ppm).
UV-Vis spectra were recorded on a VWR UV 3100PC or on a Jasco J-815 spectrophotometer using 1 cm quartz cells at 25 °C.
Steady-state fluorescence spectra were acquired on a Perkin Elmer LS45 fluorimeter using a 1 cm quartz cuvette at a right angle (RA) at 25 °C in air-equilibrated conditions.
Fluorometric solution experiments were carried out by titration of diluted solutions (6 × 10−7 M) of compound 3 in CH2Cl2 with known amounts of the analytes (fullerenes C60 and C70) using RA geometry. Fluorescence quantum yields were measured using 9,10-diphenylanthracene as fluorescence reference standard (Φ = 0.72, EtOH, air equilibrated conditions, RA) [19]. The quantum yields were determined by the slope method [20], keeping the optical densities (ODs) of the sample and reference below 0.05 at the excitation wavelength to prevent inner filter effects (IFEs).
The equilibrium constants for the supramolecular complexation (association or binding constants are referred to interchangeably throughout the text) were calculated by solving the following equation, assuming a 1:1 stoichiometry for the complex [21]:
ΔF = ½{ΔεF([H]0 + [G]0 + 1/Ka) − [ΔεF2([H]0 + [G]0 + 1/Ka)2 − 4ΔεF2[H]0[G]0]1/2}, where ΔF and ΔεF are the changes in fluorescence intensity and molar fluorescence intensity of the host upon complexation with fullerenes, Ka is the association constant, and [H]0 and [G]0 denote the initial concentrations of the host and the guest, respectively. All input data from fluorescence titration measurements were previously corrected at the excitation and emission wavelengths for the hetero-inner-filter effects (h-IFEs) resulting from the analytes using the expression Fcorr = Fobs antilog [(ODexc + ODem)/2], where ODexc and ODem are the optical densities of the solutions at the excitation and emission wavelengths [22]. Calculations were performed by a non-linear regression analysis using the Solver function in Microsoft Excel [23], with a non-linear generalized reduced gradient (GRG) algorithm and a convergence criterion for R2 < 10−9.
The lowest-energy conformers for 3:C60 and 3:C70 complexes were obtained from a molecular mechanics method (Monte Carlo method, MMFF94 force field) as implemented in Spartan’18 computational software [24].

2.2. Materials

Calix [4]arene-tripropyl-mono-iodo derivative 1 was obtained by selective mono-iodination of the corresponding 25-hydroxy-26,27,28-tripropoxycalix[4]arene [25] by an adapted synthetic procedure [26], and the details of its synthesis will be presented elsewhere. The 3,6-Diethynyl-9-propyl-9H-carbazole (2) [27] was synthesized according to our reported method. Both compounds were fully characterized by FTIR, UV-Vis, and NMR spectroscopies.
Dichlorobis(triphenylphosphine)palladium (II) (98%, Aldrich), copper(I) iodide (98%, Aldrich), Fullerene-C60 (Aldrich, 99.5%), Fullerene-C70 (Aldrich, 98%), and 9,10-diphenylanthracene (scintillation grade, Nuclear Enterprises Ltd.) were used as received. Triethylamine (99%, Riedel-de-Haën) was previously dried from CaH2 and distilled under N2 prior to use. Toluene was previously dried from Na, distilled under N2, and stored over Na. All other reagents and solvents were reagent grade and were purified and dried by standard methods. Organic extracts were dried over anhydrous magnesium sulphate.

2.3. Synthesis

The synthesis of 3 was accomplished by a Sonogashira–Hagihara cross-coupling methodology. Full experimental details will be presented elsewhere. After purification by flash chromatography, compound 3 was isolated as a light-yellow solid. The isolated fraction exhibits a cone conformation as shown by the NMR duplets of the equatorial [3.22 (d, 4H, ArCH2Ar, J = 13.1 Hz) and 3.34 (d, 4H, ArCH2Ar, J = 13.7 Hz)] and axial [4.38 (d, 4H, ArCH2Ar, J = 13.9 Hz) and 4.42 (d, 4H, ArCH2Ar, J = 13.2 Hz)] protons. The NMR spectrum of the crude reaction mixture also revealed the presence of other conformers, namely the partial cone conformer, which are currently being investigated.

3. Results and Discussion

3.1. Synthesis and Structural Characterization

The new fluorogenic calix[4]arene-carbazole dimer 3 was synthesized from calix[4]arene-tripropyl-mono-iodo derivative 1 [25,26], by a Sonogashira–Hagihara cross-coupling reaction with 3,6-diethynyl-9-propyl-9H-carbazole (2) [27] in dried toluene and NEt3, using PdCl2(PPh3)2 and CuI as catalytic system under argon (Scheme 1).
Chemproc 03 00095 sch001 550
Scheme 1. Cross-coupling of calix[4]arene-tripropyl-mono-iodo derivative (1) and 3,6-diethynyl-9-propyl-9H-carbazole (2).
Scheme 1. Cross-coupling of calix[4]arene-tripropyl-mono-iodo derivative (1) and 3,6-diethynyl-9-propyl-9H-carbazole (2).
Chemproc 03 00095 sch001
To minimize the self-condensation of carbazole units, the compound was slowly added to 1 from the onset of the reaction. By this procedure, cleaner reaction mixtures and higher isolated yields were obtained. The resultant solid is freely soluble in CH2Cl2, CHCl3, THF, cyclohexane, and toluene.
The structural characterization by FTIR and 1H/13C and 2D NMR analysis fully corroborated the proposed structure for compound 3. From FTIR analysis the absence of terminal ethynylic C≡C-H stretching vibrations characteristic of 3,6-CBZ carbazole unit [27] and the simultaneous presence of internal alkyne frequencies at 2203 cm−1 was discernible. The cone conformation of the calixarene units in dimer 3 was ascertained by the presence of a set of characteristic resonances for the protons of bridged methylene groups in the calixarene skeleton in the 1H NMR spectrum [3.22 ppm (4H, d, J = 13.1 Hz), 3.34 ppm (4H, d, J = 13.7 Hz) for equatorial protons and 4.38 ppm (4H, d, J = 13.9 Hz), 4.42 ppm (4H, d, J = 13.2 Hz) for axial protons).

3.2. Photophysical Properties

The photophysical properties of dimer 3 were studied by UV-Vis and fluorescence spectroscopies, and its ground-state absorption and steady-state luminescence spectra are shown in Figure 1. The absorption profile exhibits a peak around 320 nm at its absorption maxima, with a shoulder near 344 nm. The emission spectra revealed the most prominent band peak at 407 nm. The quantum yield (ΦF) of 3 is strongly dependent on the solvent nature. The lowest ΦF was retrieved for CHCl3 (ΦF = 0.028), followed by CH2Cl2 (ΦF = 0.13), THF (ΦF = 0.18), and cyclohexane (ΦF = 0.20). A great stability toward photobleaching was witnessed for compound 3 in CH2Cl2, the solvent used in the titration experiments with fullerenes.

3.3. Complexation Studies with Fullerenes

The ability of host 3 to form inclusion complexes with two fullerenes (C60 and C70) was assessed through fluorometric titrations in CH2Cl2 (a solvent choice trade-off between securing a reasonable quantum yield for 3 and solubilizing the fullerenes). The experiments were conducted with the guests in a concentration range of 2.04 × 10−6–2.21 × 10−5 M, while keeping that of the fluorophore constant (6.0 × 10−7 M) (Figure 2). Since both guests display absorption of radiation at the excitation (340 nm) and emission wavelengths (407 nm), correction for h-IFEs was applied (cf. Experimental section for details). Raw titration data for 3 with C60 and C70, and the corresponding curve-fitting plots, are shown in Figure 2.
Considering a neglectable dynamic quenching component for the system, and a 1:1 host-to-guest equilibrium, the association constants of the complexes were retrieved. In either case, the goodness of the fits (R2 = 0.9806 for C60 and 0.9852 for C70) indicates that a 1:1 stoichiometry was attained in the supramolecular complexes. Several remarks are in order. First of all, the binding affinities of calixarene 3 to both fullerenes are remarkable and likely the highest ever reported for calix[4]arene-based hosts. Secondly, the binding of C60 to 3 is considerably larger (Ka = 1.39 × 105 M−1) than that of C70 (Ka = 6.88 × 104 M−1), making 3 a selective host for C60 by a factor of around two. The favorable interaction of 3 with C60 may be also evaluated by the free energy change (ΔG) associated with the complex formation (ΔG = −29.33 kJ/mol for 3:C60 complex and ΔG = −27.60 kJ/mol for 3:C70 complex).
The putative structures of the complexes of 3 with the fullerene guests, obtained from conformational searches (Monte Carlo method, MMFF94 force field), are depicted in Figure 3.

4. Conclusions

A new molecular receptor-based fluorescent bis-calix[4]arene-carbazole compound was synthesized, and its ability to selectively binding C60 and C70 fullerenes was evaluated. A remarkable affinity for both fullerenes was found, as determined by fluorescence assays. It was also unveiled that the host 3 is quite sensitive to the molecular properties (molecular volume and electronic environment) of the two fullerenes. As a result, 3 can discriminate between the two fullerenes (selectivity ratio C60/C70 = 2).
No rationale for the higher binding affinity of compound 3 to C60 over C70 is presented here. Density functional theory (DFT) calculations at a significant level of theory (e.g., B3LYP-D3, wB97X-V, and M06-2X functionals with a large basis set (6-311+G(2df, 2p)) are currently under investigation to enlighten such observed selectivity. Moreover, the current study has already been extended to other bis-calix[4]arene-carbazole conjugates, namely those synthesized from 2,7-diethynyl-9-propyl-9H-carbazole units, which will certainly lead to different calixarene architectures (larger available space between the expected binding sites of calixarene moieties), with new foreseen supramolecular inclusion properties towards a variety of large organic and organometallic guests. All the above results will be published elsewhere.

Author Contributions

Conceptualization, J.V.P.; methodology, J.V.P.; investigation, S.C., A.I.C. and P.D.B.; resources, J.V.P.; data curation, J.V.P.; supervision, A.I.C. and P.D.B.; validation, A.I.C. and P.D.B.; writing—original draft preparation, A.I.C. and P.D.B.; writing—review and editing, J.V.P. All authors have read and agreed to the published version of the manuscript.

Funding

We are grateful to Fundação para a Ciência e a Tecnologia/Ministério da Ciência, Tecnologia e Ensino Superior (FCT/MCTES) for financial support (UIDB/00616/2020 and UIDP/00616/2020).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Amabilino, D.B.; Gale, P.A. Supramolecular chemistry anniversary. Chem. Soc. Rev. 2017, 46, 2376–2377. [Google Scholar] [CrossRef] [PubMed]
  2. Ma, X.; Zhao, Y. Biomedical Applications of Supramolecular Systems Based on Host−Guest Interactions. Chem. Rev. 2015, 115, 7794–7839. [Google Scholar] [CrossRef] [PubMed]
  3. Gutsche, C.D. Calixarenes-An Introduction. In Monographs in Supramolecular Chemistry, 2nd ed.; Stoddart, J.F., Ed.; The Royal Society of Chemistry: Cambridge, UK, 2008. [Google Scholar]
  4. Kumar, R.; Sharma, A.; Singh, H.; Suating, P.; Kim, H.S.; Sunwoo, K.; Shim, I.; Gibb, B.C.; Kim, J.S. Revisiting Fluorescent Calixarenes: From Molecular Sensors to Smart Materials. Chem. Rev. 2019, 119, 9657–9721. [Google Scholar] [CrossRef] [PubMed]
  5. Barata, P.D.; Prata, J.V. Cooperative Effects in the Detection of a Nitroaliphatic Liquid Explosive and an Explosive Taggant in the Vapor Phase by Calix[4]arene-Based Carbazole-Containing Conjugated Polymers. ChemPlusChem 2014, 79, 83–89. [Google Scholar] [CrossRef] [PubMed]
  6. Prata, J.V.; Costa, A.I.; Teixeira, C.M. A Solid-State Fluorescence Sensor for Nitroaromatics and Nitroanilines Based on a Conjugated Calix[4]arene Polymer. J. Fluoresc. 2020, 30, 41–50. [Google Scholar] [CrossRef] [PubMed]
  7. Prata, J.V.; Barata, P.D. Fostering protein–calixarene interactions: From molecular recognition to sensing. RSC Adv. 2016, 6, 1659–1669. [Google Scholar] [CrossRef]
  8. Anilkumar, P.; Lu, F.; Cao, L.; Luo, P.G.; Liu, J.-H.; Sahu, S.; Tackett, K.N.; Wang, Y.; Sun, Y.-P. Fullerenes for applications in biology and medicine. Curr. Med. Chem. 2011, 18, 2045–2059. [Google Scholar] [CrossRef] [PubMed]
  9. Li, C.-Z.; Yip, H.-L.; Jen, A.K.-Y. Functional fullerenes for organic photovoltaics. J. Mater. Chem. 2012, 22, 4161–4177. [Google Scholar] [CrossRef]
  10. Suzuki, T.; Nakashima, K.; Shinkai, S. Very Convenient and Efficient Purification Method for Fullerene (C60) with 5,11,17,23,29,35,41,47-Octa-tert-butylcalix[8]arene-49,50,51,52,53,54,55,56-octol. Chem. Lett. 1994, 23, 699–702. [Google Scholar] [CrossRef]
  11. Atwood, J.L.; Koutsantonis, G.A.; Raston, C.L. Purification of C60 and C70 by selective complexation with calixarenes. Nature 1994, 368, 229–231. [Google Scholar] [CrossRef]
  12. Cruz, J.L.D.; Nierengarten, J.F. Fullerenes and Calixarenes. In Calixarenes in the Nanoworld; Vicens, J., Harrowfield, J., Baklouti, L., Eds.; Springer: Dordrecht, The Netherlands, 2007; pp. 173–196. [Google Scholar]
  13. Zhong, Z.-L.; Ikeda, A.; Shinkai, S. Complexation of Fullerenes. In Calixarenes 2001; Asfari, Z., Bohmer, V., Harrowfield, J., Vicens, J., Eds.; Kluwer Academic Publishers: Dordrecht, The Netherlands, 2001; pp. 476–495. [Google Scholar]
  14. Georghiou, P.E. Calixarenes and Fullerenes. In Calixarenes and Beyond; Neri, P., Sessler, J.L., Wang, M.-X., Eds.; Springer International Publishing: Cham, Switzerland, 2016; pp. 879–919. [Google Scholar]
  15. Haino, T.; Yanase, M.; Fukunaga, C.; Fukazawa, Y. Fullerene encapsulation with calix[5]arenes. Tetrahedron 2006, 62, 2025–2035. [Google Scholar] [CrossRef]
  16. Halder, A.; Nayak, S.K.; Chattopadhyay, S.; Bhattacharya, S. A Rational Approach Towards Determination of Optical Ionicity and Non-covalent Interactions in Fullerene-Calix[4]arene Host-Guest Complexes. J. Solution Chem. 2012, 41, 223–240. [Google Scholar] [CrossRef]
  17. Kás, M.; Lang, K.; Stibora, I.; Lhoták, P. Novel fullerene receptors based on calixarene–porphyrin conjugates. Tetrahedron Lett. 2007, 48, 477–481. [Google Scholar] [CrossRef]
  18. Golan, A.; Goldberg, I.; Vigalok, A. Synthesis and C70 complexation studies of a fluorescent 5,5′-bi-p-tert-butylcalix[4]arene scaffold. Supramol. Chem. 2016, 28, 526–535. [Google Scholar] [CrossRef]
  19. Eaton, D.F. Reference materials for fluorescence measurement. Pure Appl. Chem. 1988, 60, 1107–1114. [Google Scholar] [CrossRef]
  20. A Guide to Recording Fluorescence Quantum Yields, Horiba Scientific. Available online: http://www.horiba.com/fileadmin/uploads/Scientific/Documents/Fluorescence/quantumyieldstrad.pdf (accessed on 5 November 2020).
  21. Liu, Y.; Han, B.-H.; Chen, Y.-T. Molecular Recognition and Complexation Thermodynamics of Dye Guest Molecules by Modified Cyclodextrins and Calixarenesulfonates. J. Phys. Chem. B 2002, 106, 4678–4687. [Google Scholar] [CrossRef]
  22. Lakowicz, J.R. Principles of Fluorescence Spectroscopy, 3rd ed.; Springer: New York, NY, USA, 2006; p. 56. [Google Scholar]
  23. Brown, A.M. A step-by-step guide to non-linear regression analysis of experimental data using a Microsoft Excel spreadsheet. Comput. Meth. Programs Biomed. 2001, 65, 191–200. [Google Scholar] [CrossRef]
  24. Spartan’18; Wavefunction Inc.: Irvine, CA, USA, 2019.
  25. Dondoni, A.; Ghiglione, C.; Marra, A.; Scoponi, M. Synthesis of Calix[4]arenylvinylene and Calix[4]arenylphenylene Oligomers by Stille and Suzuki Cross-Coupling Reactions. J. Org. Chem. 1998, 63, 9535–9539. [Google Scholar] [CrossRef]
  26. Bovonsombat, P.; Leykajarakul, J.; Khan, C.; Pla-on, K.; Krause, M.M.; Khanthapura, P.; Ali, R.; Doowa, N. Regioselective iodination of phenol and analogues using N-iodosuccinimide and p-toluenesulfonic acid. Tetrahedron Lett. 2009, 50, 2664–2667. [Google Scholar] [CrossRef]
  27. Barata, P.D.; Costa, A.I.; Prata, J.V. Calix[4]arene-carbazole-containing polymers: Synthesis and properties. React. Funct. Polym. 2012, 72, 627–634. [Google Scholar] [CrossRef]
Chemproc 03 00095 g001 550
Figure 1. Absorption (2.5 × 10−5 M) and fluorescence (6.0 × 10−7 M, λexc = 340 nm) spectra of dimer 3 in CH2Cl2.
Figure 1. Absorption (2.5 × 10−5 M) and fluorescence (6.0 × 10−7 M, λexc = 340 nm) spectra of dimer 3 in CH2Cl2.
Chemproc 03 00095 g001
Chemproc 03 00095 g002 550
Figure 2. Emission spectra of 3 (6.0 × 10−7 M in CH2Cl2) after successive additions (2.04 × 10−6 - 2.21 × 10−5 M) of fullerene C60 (a) and C70 (b); curve-fitting plots for C60 (c) and C70 (d) derived from a non-linear regression analysis of the fluorescence data (λexc = 340 nm).
Figure 2. Emission spectra of 3 (6.0 × 10−7 M in CH2Cl2) after successive additions (2.04 × 10−6 - 2.21 × 10−5 M) of fullerene C60 (a) and C70 (b); curve-fitting plots for C60 (c) and C70 (d) derived from a non-linear regression analysis of the fluorescence data (λexc = 340 nm).
Chemproc 03 00095 g002
Chemproc 03 00095 g003 550
Figure 3. Best conformers of C60 (a) and C70 (b) complexes with calixarene 3, after Monte Carlo/MMFF94 molecular mechanics calculations [24].
Figure 3. Best conformers of C60 (a) and C70 (b) complexes with calixarene 3, after Monte Carlo/MMFF94 molecular mechanics calculations [24].
Chemproc 03 00095 g003
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Costa, S.; Barata, P.D.; Costa, A.I.; Prata, J.V. A New Fluorescent Calixarene Dimer: Synthesis, Optical Properties, and Sensory Applications. Chem. Proc. 2021, 3, 95. https://0-doi-org.brum.beds.ac.uk/10.3390/ecsoc-24-08340

AMA Style

Costa S, Barata PD, Costa AI, Prata JV. A New Fluorescent Calixarene Dimer: Synthesis, Optical Properties, and Sensory Applications. Chemistry Proceedings. 2021; 3(1):95. https://0-doi-org.brum.beds.ac.uk/10.3390/ecsoc-24-08340

Chicago/Turabian Style

Costa, Sérgio, Patrícia D. Barata, Alexandra I. Costa, and José V. Prata. 2021. "A New Fluorescent Calixarene Dimer: Synthesis, Optical Properties, and Sensory Applications" Chemistry Proceedings 3, no. 1: 95. https://0-doi-org.brum.beds.ac.uk/10.3390/ecsoc-24-08340

Article Metrics

Back to TopTop