Luminescent hollow micro- and nanocrystals have been successfully obtained taking advantage of the self-assembly behavior and the aggregation-induced emission enhancement properties of several bispyrazolate Pt(II) metallomesogens decorated with four terminal alkyl chains. Oil-in-water droplets have been used to confine the Pt(II) compounds and drive them to be self-assembled via intermolecular Pt···Pt interactions into spherical aggregates of about 200 or 50 nm. Evaporation of the oil phase generates highly-stable aqueous dispersions of nanocrystals that emit a bright orange light as a result of the existence of 3MMLCT excited states. Different methods and conditions have been tested for studying the effect of several parameters such as the temperature and the stirring speed in the final particle size and in the polydispersity index. Moreover, the micro- and nanocrystals are able to entrap hydrophobic drugs between the alkyl chains of the compounds, forming stable dispersions of drug-loaded capsules in water. The droplet method is applied in the area of metallomesogens for the first time to synthesize self-assembled Pt(II) nanocapsules, which opens a new field of study that could allow the use of these liquid crystal materials in biomedical applications.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Price excludes VAT (USA)
Tax calculation will be finalised during checkout.
Jenekhe, S. A.; Osaheni, J. A. Excimers and exciplexes of conjugated polymers. Science 1994, 265, 765–768.
Zhao, N.; Lam, J. W. Y.; Sung, H. H. Y.; Min Su, H.; Williams, I. D.; Wong, K. S.; Tang, B. Z. Effect of the counterion on light emission: a displacement strategy to change the emission behaviour from aggregation-caused quenching to aggregation-induced emission and to construct sensitive fluorescent sensors for Hg2+ detection. Chem. Eur. J. 2014, 20, 133–138.
Qi, J. P.; Hu, X. W.; Dong, X. C.; Lu, Y.; Lu, H. P.; Zhao, W. L.; Wu, W. Towards more accurate bioimaging of drug nanocarriers: Turning aggregation-caused quenching into a useful tool. Adv. Drug Deliv. Rev. 2019, 143, 206–225.
Wu, H.; Zhang, L.; Yang, J. F.; Bo, R. N.; Du, H. X.; Lin, K.; Zhang, D. L.; Ramachandran, M.; Shen, Y. B.; Xu, Y. X. et al. Rotatable aggregation-induced-emission/aggregation-caused-quenching ratio strategy for real-time tracking nanoparticle dynamics. Adv. Funct. Mater. 2020, 14, 1910348.
Wang, H.; Zhao, E. G.; Lam, J. W. Y.; Tang, B. Z. AIE luminogens: Emission brightened by aggregation. Mater. Today 2015, 18, 365–377.
Tian, W. G.; Zhang, J. M.; Yu, J.; Wu, J.; Nawaz, H.; Zhang, J.; He, J. S.; Wang, F. S. Cellulose - based solid fluorescent materials. Adv. Opt. Mater. 2016, 4, 2044–2050
Hu, R. R.; Leung, N. L. C.; Tang, B. Z. AIE macromolecules: syntheses, structures and functionalities. Chem. Soc. Rev. 2014, 43, 4494–4562.
Hong, Y. N.; Lam, J. W. Y.; Tang, B. Z. Aggregation-induced emission: Phenomenon, mechanism and applications. Chem. Commun. 2009, 4332–4353.
Luo, J. D.; Xie, Z. L.; Lam, J. W. Y.; Cheng, L.; Chen, H. Y.; Qiu, C. F.; Kwok, H. S.; Zhan, X. W.; Liu, Y. Q.; Zhu, D. B. et al. Aggregation-induced emission of 1-methyl-1,2,3,4,5-pentaphenylsilole. Chem. Commun. 2001, 1740–1741.
Tang, B. Z.; Zhan, X. W.; Yu, G.; Lee, P. P. S.; Liu, Y. Q.; Zhu, D. B. Efficient blue emission from siloles. J. Mater. Chem. 2001, 11, 2974–2978.
Guo, Z. Q.; Yan, C. X.; Zhu, W. H. High-performance quinoline-malononitrile core as a building block for the diversity-oriented synthesis of AIEgens. Angew. Chem., Int. Ed. 2020, 59, 9812–9825.
Chen, Z.; Zhang, J.; Song, M.; Yin, J.; Yu, G. A.; Liu, S. H. A novel fluorene-based aggregation-induced emission (AIE)-active gold(i) complex with crystallization-induced emission enhancement (CIEE) and reversible mechanochromism characteristics. Chem. Commun. 2015, 51, 326–329.
Zhao, F.; Chen, Z.; Fan, C. B.; Liu, G.; Pu, S. Z. Aggregation-induced emission (AIE)-active highly emissive novel carbazole-based dyes with various solid-state fluorescence and reversible mechanofluorochromism characteristics. Dyes Pigments 2019, 164, 390–397.
Hou, X. G.; Wu, Y.; Cao, H. T.; Sun, H. Z.; Li, H. B.; Shan, G. G.; Su, Z. M. A cationic iridium(III) complex with aggregation-induced emission (AIE) properties for highly selective detection of explosives. Chem. Commun. 2014, 50, 6031–6034.
Gao, H. Z.; Xu, D. F.; Wang, Y. H.; Wang, Y. H.; Liu, X. L.; Han, A. X.; Zhang, C. Effects of alkyl chain length on aggregation-induced emission, self-assembly and mechanofluorochromism of tetraphenylethene modified multifunctional β-diketonate boron complexes. Dyes Pigments 2018, 150, 59–66.
Chowdhury, A.; Howlader, P.; Mukherjee, P. S. Aggregation-induced emission of platinum(II) metallacycles and their ability to detect nitroaromatics. Chem. Eur. J. 2016, 22, 7468–7478.
Li, P.; Zeng, Q. Y.; Sun, H. Z.; Akhtar, M.; Shan, G. G.; Hou, X. G.; Li, F. S.; Su, Z. M. Aggregation-induced emission (AIE) active iridium complexes toward highly efficient single-layer non-doped electroluminescent devices. J. Mater. Chem. C 2016, 4, 10464–10470.
Proetto, M. T.; Sanning, J.; Peterlechner, M.; Thunemann, M.; Stegemann, L.; Sadegh, S.; Devor, A.; Gianneschi, N. C.; Strassert, C. A. Phosphorescent Pt(II) complexes spatially arrayed in micellar polymeric nanoparticles providing dual readout for multimodal imaging. Chem. Commun. 2019, 55, 501–504.
Wu, Y. P.; Tan, X.; Lv, A. Q.; Yu, F. L.; Ma, H. L.; Shen, K.; Sun, Z. Y.; Chen, F.; Chen, Z. K.; Hang, X. C. Triplet excited-state engineering of phosphorescent Pt(II) complexes. J. Phys. Chem. Lett. 2019, 10, 5105–5110.
Li, K.; Tong, G. S. M.; Wan, Q. Y.; Cheng, G.; Tong, W. Y.; Ang, W. H.; Kwong, W. L.; Che, C. M. Highly phosphorescent platinum(II) emitters: Photophysics, materials and biological applications. Chem. Sci. 2016, 7, 1653–1673.
Liu, L. J.; Wang, X.; Wang, N.; Peng, T.; Wang, S. N. Bright, multi-responsive, sky-blue Platinum(II) phosphors based on a tetradentate chelating framework. Angew. Chem., Int. Ed. 2017, 24, 9288–9292.
Ganesan, P.; Hung, W. Y.; Tso, J. Y.; Ko, C. L.; Wang, T. H.; Chen, P. T.; Hsu, H. F.; Liu, S. H.; Lee, G. H.; Chou, P. T. et al. Functional pyrimidinyl pyrazolate Pt(II) complexes: Role of nitrogen atom in tuning the solid - state stacking and photophysics. Adv. Funct. Mater. 2019, 29, 1900923.
Fu, T. F.; Ao, L.; Gao, Z. C.; Zhang, X. L.; Wang, F. Advances on supramolecular assembly of cyclometalated platinum(II) complexes. Chin. Chem. Lett. 2016, 27, 1147–1154.
Wu, J. T.; Li, Y. Q.; Tan, C. Y.; Wang, X.; Zhang, Y. M.; Song, J.; Qu, J. L.; Wong, W. Y. Aggregation-induced near-infrared emitting platinum(II) terpyridyl complex: Cellular characterisation and lysosomespecific localisation. Chem. Commun. 2018, 54, 11144–11147.
Gao, L. R.; Ni, J.; Su, M. M.; Kang, J. J.; Zhang, J. J. Luminescence switching property of cycloplatinated(II) complexes bearing 2-phenylpyridine derivatives and the application for data security storage. Dyes Pigments 2019, 165, 231–238.
Li, R.; Xu, F. F.; Gong, Z. L.; Zhong, Y. W. Thermo-responsive light-emitting metal complexes and related materials. Inorg. Chem. Front. 2020, 7, 3258–3281.
Cuerva, C.; Campo, J. A.; Ovejero, P.; Torres, M. R.; Oliveira, E.; Santos, S. M.; Lodeiro, C.; Cano, M. Columnar discotic Pt(II) metallomesogens as luminescence multifunctional materials with chemo and thermosensor abilities. J. Mater. Chem. C 2014, 2, 9167–9181.
Cuerva, C.; Campo, J. A.; Cano, M.; Lodeiro, C. Platinum(II) metallomesogens: New external-stimuli-responsive photoluminescence materials. Chem. Eur. J. 2016, 22, 10168–10178.
Cuerva, C.; Campo, J. A.; Cano, M.; Lodeiro, C. Multi-stimuliresponsive properties of aggregation-enhanced emission-active unsymmetrical PtII metallomesogens through self-assembly. Chem. Eur. J. 2019, 25, 12046–12051.
Cuerva, C.; Campo, J. A.; Cano, M.; Caño-García, M.; Otón, J. M.; Lodeiro, C. Aggregation-induced emission enhancement (AIEE)-active Pt(II) metallomesogens as dyes sensitive to Hg2+ and dopant agents to develop stimuli-responsive luminescent polymer materials. Dyes Pigments 2020, 175, 108098.
Giménez, N.; Lalinde, E.; Lara, R.; Moreno, M. T. Design of luminescent, heteroleptic, cyclometalated PtII and PtIV complexes: Photophysics and effects of the cyclometalated ligands. Chem. Eur. J. 2019, 25, 5514–5526.
Chang, S. Y.; Kavitha, J.; Hung, J. Y.; Chi, Y.; Cheng, Y. M.; Li, E. Y.; Chou, P. T.; Lee, G. H.; Carty, A. J. Luminescent platinum(II) complexes containing isoquinolinyl indazolate ligands: Synthetic reaction pathway and photophysical properties. Inorg. Chem. 2007, 46, 7064–7074.
Ku, H. Y.; Tong, B. H.; Chi, Y.; Kao, H. C.; Yeh, C. C.; Chang, C. H.; Lee, G. H. Luminescent Pt(II) complexes bearing dual isoquinolinyl pyrazolates: Fundamentals and applications. Dalton Trans. 2015, 44, 8552–8563.
Ogasawara, M.; Lin, X.; Kurata, H.; Ouchi, H.; Yamauchi, M.; Ohba, T.; Kajitani, T.; Fukushima, T.; Numata, M.; Nogami, R. et al. Water-induced self-assembly of an amphiphilic perylene bisimide dyad into vesicles, fibers, coils, and rings. Mater. Chem. Front. 2018, 2, 171–179.
Sun, Y. X.; Mei, L.; Han, N.; Ding, X. Y.; Yu, C. H.; Yang, W. J.; Ruan, G. Examining the roles of emulsion droplet size and surfactant in the interfacial instability-based fabrication process of micellar nanocrystals. Nanoscale Res. Lett. 2017, 12, 434.
Piorkowski, D. T.; McClements, D. J. Beverage emulsions: Recent developments in formulation, production, and applications. Food Hydrocoll. 2014, 42, 5–41.
Aliprandi, A.; Mauro, M.; De Cola, L. Controlling and imaging biomimetic self-assembly. Nat. Chem. 2016, 8, 10–15.
Liao, C. T.; Chen, H. H.; Hsu, H. F.; Poloek, A.; Yeh, H. H.; Chi, Y.; Wang, K. W.; Lai, C. H.; Lee, G. H.; Shih, C. W. et al. Mesomorphism and luminescence properties of platinum(II) complexes with tris(alkoxy)phenyl-functionalized pyridyl pyrazolate chelates. Chem. Eur. J. 2011, 17, 546–556.
Banerjee, R.; Purkayastha, P. Revival of the nearly extinct fluorescence of coumarin 6 in water and complete transfer of energy to rhodamine 123. Soft Matter 2017, 13, 5506–5508.
Banerjee, R.; Mondal, S.; Purkayastha, P. Revival, enhancement and tuning of fluorescence from Coumarin 6: Combination of host-guest chemistry, viscosity and collisional quenching. RSC Adv. 2016, 6, 105347–105349.
Banerjee, R.; Sinha, R.; Purkayast, P. β-Cyclodextrin encapsulated coumarin 6 on graphene oxide nanosheets: Impact on ground-state electron transfer and excited-state energy transfer. ACS Omega 2019, 4, 16153–16158.
Ma, W. X.; Chen, M. S.; Kaushal, S.; McElroy, M.; Zhang, Y.; Ozkan, C.; Bouvet, M.; Kruse, C.; Grotjahn, D.; Ichim, T. et al. PLGA nanoparticle-mediated delivery of tumor antigenic peptides elicits effective immune responses. Int. J. Nanomedicine 2012, 7, 1475–1487.
This work was supported by the Associate Laboratory for Green Chemistry-LAQV, which is financed by national funds from FCT/MCTES (No. UIDB/50006/2020), and the PROTEOMASS Scientific Society (general funds). C. C. acknowledges the Spanish Foundation Alfonso Martín Escudero for his postdoctoral fellowship. J. F. L. thanks FCT/MEC (Portugal) the junior researcher contract under DL/57 programme.
In loving memory of Prof. José A. Campo Santillana.
Electronic Supplementary Material
Rights and permissions
About this article
Cite this article
Cuerva, C., Fernández-Lodeiro, J., Cano, M. et al. Water-soluble hollow nanocrystals from self-assembly of AIEE-active Pt(II) metallomesogens. Nano Res. 14, 245–254 (2021). https://doi.org/10.1007/s12274-020-3078-0
- Pt(II) metallomesogens
- luminescent nanomaterials