Molecules 2020, 25, 3702
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of a 9:1 mixture of Z-CA and E-CA (total concentration of 1.62 mM) in D2O (pD 6) at 298 K (400 MHz); Figure S19.
1H NMR spectra of (a) E-CA (1.62 mM), (b) after irradiation of UV light (300 nm) to (a) for 5 min, (c) E-CA/CB7
(1.62 mM for E-CA and 3.46 mM for CB7), and (d) after irradiation of UV light (300 nm) to (b) for 5 min in D2O
(pD 6) at 298 K (400 MHz). Solvent and CB7 peaks are indicated; Figure S20. 1H NMR spectra of (a) a 9:1 mixture
of Z-CA and E-CA (total concentration of 1.62 mM), (b) after irradiation of UV light (254 nm) to (a) for 10 min,
(c) a mixture of Z-CA and E-CA/CB7 (total concentration of 1.62 mM for CA and 3.46 mM for CB7), and (d) after
irradiation of UV light (254 nm) to (b) for 10 min in D2O (pD 6) at 298 K (400 MHz). Solvent and CB7 peaks are
indicated; Figure S21 Calibration curves for (a) E-CA, and (b) E-CA/CB7 complex plotted using the values in
Table S3; Table S1. The measured percentages associated with the E to Z photoisomerization upon irradiation of
300 nm to a solution of E-CA (1.62 mM) in D2O at pD 6; Table S2. The measured percentages associated with the Z
to E photoisomerization upon irradiation of 254 nm to a mixture of Z-CA isomer and E-CA (Z-CA:E-CA = 9:1)
isomer in D2O at pD 6; Table S3. Absorbances (Abs.) data of E-CA (16 µM in water and 32 µM in CB7) at 276 nm
in the absence and presence of CB7 (1 mM) associated with the E to Z photoisomerization upon irradiation of UV
light (300 nm); Table S4. The calculated percentages of E-CA and E-CA/CB7 associated with alternating irradiation
of 300 nm (3 min) and 254 nm (3 min) from the absorbances (Abs.) data in Figures S13 and S14.
Author Contributions: Formal analysis, H.A.-A., A.A.-A., and Z.M.; writing—original draft preparation, R.B.
and M.S.B.; conceptualization; methodology; data curation; writing—review and editing; supervision; project
administration, N.S.; funding acquisition, N.S., M.S.B., and Z.M. All authors have read and agreed to the published
version of the manuscript.
Funding: We thank the research program in United Arab Emirates University for financial grant number UPAR
(2020) 31S392 and Start-up (2019) 31S401 from the UAE University.
Conflicts of Interest: The authors declare no conflict of interest.
References
1.
Lunkenbein, S.; Bellido, M.; Aharoni, A.; Salentijn, E.M.J.; Kaldenhoff, R.; Coiner, H.A.; Muñoz-Blanco, J.;
Schwab, W. Cinnamate metabolism in ripening fruit. Characterization of a UDP-glucose: Cinnamate
glucosyltransferase from strawberry. Plant Physiol. 2006, 140, 1047–1058. [PubMed]
2.
Steenackers, W.; El Houari, I.; Baekelandt, A.; Witvrouw, K.; Dhondt, S.; Leroux, O.; Gonzalez, N.; Corneillie, S.;
Cesarino, I.; Inzé, D.; et al. Cis-cinnamic acid is a natural plant growth-promoting compound. J. Exp. Bot.
3.
4.
5.
6.
7.
8.
9.
Lewis, F.D.; Oxman, J.D.; Gibson, L.L.; Hampsch, H.L.; Quillen, S.L. Lewis acid catalysis of photochemical
reactions. 4. Selective isomerization of cinnamic esters. J. Am. Chem. Soc. 1986, 108, 3005–3015. [CrossRef]
Karthikeyan, S.; Ramamurthy, V. Templating photodimerization of trans-cinnamic acid esters with a
water-soluble pd nanocage. J. Org. Chem. 2007, 72, 452–458. [CrossRef] [PubMed]
Parthasarathy, A.; Samanta, S.R.; Ramamurthy, V. Photodimerization of hydrophobic guests within a
water–soluble nanocapsule. Res. Chem. Intermed. 2013, 39, 73–87. [CrossRef]
Kim, Y.; Ko, Y.H.; Jung, M.; Selvapalam, N.; Kim, K. A new photo-switchable “on-off” host–guest system.
Photochem. Photobiol. Sci. 2011, 10, 1415–1419. [CrossRef]
Al-Rawashdeh, N.A.F.; Al-Sadeh, K.S.; Al-Bitar, M.-B. Physicochemical study on microencapsulation of
hydroxypropyl-β-cyclodextrin in dermal preparations. Drug Dev. Ind. Pharm. 2010, 36, 688–697. [CrossRef]
Das, D.; Assaf, K.I.; Nau, W.M. Applications of cucurbiturils in medicinal chemistry and chemical biology.
Astray, G.; Gonzalez-Barreiro, C.; Mejuto, J.C.; Rial-Otero, R.; Simal-Gándara, J. A review on the use of
cyclodextrins in foods. Food Hydrocoll. 2009, 23, 1631–1640. [CrossRef]
10. Ciobanu, A.; Landy, D.; Fourmentin, S. Complexation efficiency of cyclodextrins for volatile flavor compounds.
Food Res. Int. 2013, 53, 110–114. [CrossRef]
11. Kfoury, M.; Auezova, L.; Greige-Gerges, H.; Fourmentin, S. Promising applications of cyclodextrins in food:
Improvement of essential oils retention, controlled release and antiradical activity. Carbohydr. Polym. 2015
,
12. Szente, L.; Szejtli, J. Cyclodextrins as food ingredients. Trends Food Sci. Tech. 2004, 15, 137–142. [CrossRef]
13. Zhang, Q.; Zhen, Z.; Jiang, H.; Li, X.-G.; Liu, J.-A. Encapsulation of the ethylene inhibitor
1-methylcyclopropene by cucurbit[6]uril. J. Agric. Food Chem. 2011, 59, 10539–10545. [CrossRef] [PubMed]
14. Nuzzo, A.; Scherman, O.A.; Mazzei, P.; Piccolo, A. pH-controlled release of auxin plant hormones from
cucurbit[7]uril macrocycle. Chem. Biol. Tech. Agric. 2014, 1, 2. [CrossRef]