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Different alkali deep eutectic solvents (DES), such as LiI:nEG, NaI:nEG, and KI:nEG, have been tested as electrolytes for dye sensitized solar cells (DSSCs). These DSSCs were prepared using pure DES or, alternatively, DES combined with different amounts of iodine (I2). The most important parameters, such as open circuit voltage (VOC), short circuit current density (JSC), fill factor (FF), and the overall conversion efficiency (η), were evaluated. Some DES seem to be promising candidates for DSSC applications, since they present higher VOC (up to 140 mV), similar FF values but less current density values, when compared with a reference electrolyte in the same experimental conditions. Additionally, electrochemical impedance spectroscopy (EIS) has been performed to elucidate the charge transfer and transport processes that occur in DSSCs. The values of different resistance (Ω·cm2) phenomena and recombination/relaxation time (s) for each process have been calculated. The best-performance was obtained for DES-based electrolyte, KI:EG (containing 0.5 mol% I2) showing an efficiency of 2.3%. The efficiency of this DES-based electrolyte is comparable to other literature systems, but the device stability is higher (only after seven months the performance of the device drop to 60%).
Hugo Cruz; Ana Pinto; Noémi Jordão; Luísa Neves; Luís Branco. Alkali Iodide Deep Eutectic Solvents as Alternative Electrolytes for Dye Sensitized Solar Cells. Sustainable Chemistry 2021, 2, 222 -236.
AMA StyleHugo Cruz, Ana Pinto, Noémi Jordão, Luísa Neves, Luís Branco. Alkali Iodide Deep Eutectic Solvents as Alternative Electrolytes for Dye Sensitized Solar Cells. Sustainable Chemistry. 2021; 2 (2):222-236.
Chicago/Turabian StyleHugo Cruz; Ana Pinto; Noémi Jordão; Luísa Neves; Luís Branco. 2021. "Alkali Iodide Deep Eutectic Solvents as Alternative Electrolytes for Dye Sensitized Solar Cells." Sustainable Chemistry 2, no. 2: 222-236.
We report on the application of novel small-molecule highly crystalline pentacyclic diamides possessing significant OTFT and OLED potential.
Carolina S. Marques; Hugo Cruz; Simon E. Lawrence; Sandra Gago; João P. Prates Ramalho; Jorge Morgado; Luís C. Branco; Anthony J. Burke. Ambipolar pentacyclic diamides with interesting electrochemical and optoelectronic properties. Chemical Communications 2020, 56, 14893 -14896.
AMA StyleCarolina S. Marques, Hugo Cruz, Simon E. Lawrence, Sandra Gago, João P. Prates Ramalho, Jorge Morgado, Luís C. Branco, Anthony J. Burke. Ambipolar pentacyclic diamides with interesting electrochemical and optoelectronic properties. Chemical Communications. 2020; 56 (94):14893-14896.
Chicago/Turabian StyleCarolina S. Marques; Hugo Cruz; Simon E. Lawrence; Sandra Gago; João P. Prates Ramalho; Jorge Morgado; Luís C. Branco; Anthony J. Burke. 2020. "Ambipolar pentacyclic diamides with interesting electrochemical and optoelectronic properties." Chemical Communications 56, no. 94: 14893-14896.
Deep eutectic solvents (DES) composed of lithium, sodium, or potassium iodide salts in suitable combination with ethylene glycol (EG), glycerol (Gly), or polyethylene glycol (PEG) have been developed. All prepared DES were characterized by thermal analysis (DSC and TGA) and its complex conductivity (σ*) and impedance (Z*) frequency were evaluated through dielectric relaxation spectroscopy (DRS). Two- and three-electrode electrochemical studies of all DES have been performed. All DES avoid crystallization, exhibiting conductivity values in a range from 10–4 to 10–2 S cm–1 at room temperature and electrochemical windows higher than 1 V (on the order of 3–4 V), fulfilling the usual suitability criteria for utilization in electrochromic devices (ECD). The most promissory DES as electrolytes were tested for ECD. Being suitable candidates for further application in batteries.
Hugo Cruz; Noemi Jordao; Ana Lucia Pinto; Madalena Dionisio; Luisa A. Neves; Luis C. Branco. Alkaline Iodide-Based Deep Eutectic Solvents for Electrochemical Applications. ACS Sustainable Chemistry & Engineering 2020, 1 .
AMA StyleHugo Cruz, Noemi Jordao, Ana Lucia Pinto, Madalena Dionisio, Luisa A. Neves, Luis C. Branco. Alkaline Iodide-Based Deep Eutectic Solvents for Electrochemical Applications. ACS Sustainable Chemistry & Engineering. 2020; ():1.
Chicago/Turabian StyleHugo Cruz; Noemi Jordao; Ana Lucia Pinto; Madalena Dionisio; Luisa A. Neves; Luis C. Branco. 2020. "Alkaline Iodide-Based Deep Eutectic Solvents for Electrochemical Applications." ACS Sustainable Chemistry & Engineering , no. : 1.
Polyoxometalates (POMs) as anionic metal oxides are promising candidates for application in dye-sensitized solar cells (DSSCs) due to their peculiar properties including a reversible and multi-electron redox behavior. In this work, four polyoxometalate as ionic liquids (POM-ILs) based on the combination between phosphomolybdate anion (PMo12O403−) and organic cations such as [BMIM]+, [BPy]+, [HDPy]+ and [P6,6,6,14]+ were prepared and characterized. A detailed chemical structural elucidation by elemental analysis, ATR-FTIR, 1H and 31P NMR spectroscopies have been performed. These POM-ILs were tested as photosensitizers by adsorption to the photoanode (TiO2 film) for different times (15 min to 17 h). The DSSCs performance can be highly improved comparing the commercially available compound and POM-ILs. The electrodeposition process is an excellent alternative to adsorption in order to improve the overall efficiencies. In general, [BPy]3[PMo12O40] and [P6,6,6,14]3[PMo12O40] are the most promissory compounds for DSSC approaches.
Hugo Cruz; Ana Lucia Pinto; João Carlos Lima; Luís C. Branco; Sandra Gago. Application of polyoxometalate-ionic liquids (POM-ILs) in dye-sensitized solar cells (DSSCs). Materials Letters: X 2019, 6, 100033 .
AMA StyleHugo Cruz, Ana Lucia Pinto, João Carlos Lima, Luís C. Branco, Sandra Gago. Application of polyoxometalate-ionic liquids (POM-ILs) in dye-sensitized solar cells (DSSCs). Materials Letters: X. 2019; 6 ():100033.
Chicago/Turabian StyleHugo Cruz; Ana Lucia Pinto; João Carlos Lima; Luís C. Branco; Sandra Gago. 2019. "Application of polyoxometalate-ionic liquids (POM-ILs) in dye-sensitized solar cells (DSSCs)." Materials Letters: X 6, no. : 100033.
A pH-, light- and redox-responsive flavylium-bipyridinium molecular dyad (bioinspired in natural anthocyanins) was synthesized and employed to devise a pseudorotaxane with the macrocycle cucurbit[7]uril (CB7) in aqueous solution. The inclusion complex was characterized by UV-Vis absorption, fluorescence emission, NMR and electrochemical techniques which demonstrate formation of a stable binary complex between the dyad and CB7 both under acidic and neutral conditions. It is noteworthy that the flavylium-bipyridinium tricationic dyad is only stable in highly acidic media, undergoing a reversible hydration reaction at slightly acidic or neutral pH to give a trans-chalcone-bipyridinium dication. 1H NMR experiments showed that in this last species the CB7 binds to the bipyridinium unit while in the tricationic species the macrocycle is positioned between the flavylium and the bipyridinium moieties. The different location of the CB7 wheel in the two dyad states allows control of the shuttling movement using light and pH stimuli that trigger the interconversion between these two species.
André Seco; Ana Marta Alves Diniz; João Sarrato; Henrique Mourão; Hugo Cruz; A. Jorge Parola; Nuno Basílio. A pseudorotaxane formed from a cucurbit[7]uril wheel and a bioinspired molecular axle with pH, light and redox-responsive properties. Pure and Applied Chemistry 2019, 92, 301 -313.
AMA StyleAndré Seco, Ana Marta Alves Diniz, João Sarrato, Henrique Mourão, Hugo Cruz, A. Jorge Parola, Nuno Basílio. A pseudorotaxane formed from a cucurbit[7]uril wheel and a bioinspired molecular axle with pH, light and redox-responsive properties. Pure and Applied Chemistry. 2019; 92 (2):301-313.
Chicago/Turabian StyleAndré Seco; Ana Marta Alves Diniz; João Sarrato; Henrique Mourão; Hugo Cruz; A. Jorge Parola; Nuno Basílio. 2019. "A pseudorotaxane formed from a cucurbit[7]uril wheel and a bioinspired molecular axle with pH, light and redox-responsive properties." Pure and Applied Chemistry 92, no. 2: 301-313.
Anthocyanins are the main polyphenolic dyes found in young red wines, which are transformed into more stable structures such as pyranoanthocyanins, during wine ageing and maturation. While anthocyanins practically lose their red color between pH 1 and 5, as a result of the formation of colorless hemiketals, pyranoanthocyanins practically do not change their color intensity. For that they constitute a photosensitizer family with great potential for bio-inspired dye-sensitized solar cells (DSSCs). In this work, a series of pyranoanthocyanin derivatives were designed, synthesized and applied for the first time as dye sensitizers in DSSCs. A relation was established between dye structure and cell efficiency. Specifically, the influence of different linker units, carboxyl and catechol, was studied in terms of their influence in the various parameters related to DSSC efficiency. The presence of the catechol unit was shown to be essential for efficient electron injection of the dye into the TiO2 semiconductor, since carboxylic units showed a deleterious effect in electron injection due to their electron withdrawing character. An overall efficiency of 1.15% was obtained for the best performing compound, 10-catecholpyrano-3′,4’,5,7-tetrahydroxyflavylium, with no further optimization.
Ana Lucia Pinto; Luis Cruz; Vânia Gomes; Hugo Cruz; Giuseppe Calogero; Victor Freitas; Fernando Pina; A. Jorge Parola; J. Carlos Lima. Catechol versus carboxyl linkage impact on DSSC performance of synthetic pyranoflavylium salts. Dyes and Pigments 2019, 170, 107577 .
AMA StyleAna Lucia Pinto, Luis Cruz, Vânia Gomes, Hugo Cruz, Giuseppe Calogero, Victor Freitas, Fernando Pina, A. Jorge Parola, J. Carlos Lima. Catechol versus carboxyl linkage impact on DSSC performance of synthetic pyranoflavylium salts. Dyes and Pigments. 2019; 170 ():107577.
Chicago/Turabian StyleAna Lucia Pinto; Luis Cruz; Vânia Gomes; Hugo Cruz; Giuseppe Calogero; Victor Freitas; Fernando Pina; A. Jorge Parola; J. Carlos Lima. 2019. "Catechol versus carboxyl linkage impact on DSSC performance of synthetic pyranoflavylium salts." Dyes and Pigments 170, no. : 107577.
Two photochromic room‐temperature ionic liquids (RTILs) based on anionic diarylethene derivative (DTE) were synthesized and characterized. Photochemical (quantum yields for ring closure and opening) and electrochemical (cyclic voltammetry) properties of the [ALIQUAT]2[DTE] and [P6,6,6,14]2[DTE] compounds as amorphous salts have been investigated. All compounds (including the di‐acid precursor and two RTILs) were studied in solution, in their intrinsically pure forms (RTIL as unique media) and in the solid state (BaSO4 support). Combination with larger organic cations can stabilize the closed‐ring form, apparently avoiding the formation of by‐products without photodegradation. It is observed that the closed‐ring reaction is faster in the case of RTILs comparing to the di‐acid starting material. The coloration switches between transparent (initial state) to purple ([ALIQUAT]2[DTE]) or pink ([P6,6,6,14]2[DTE]). The novel diarylethene‐based RTILs as multi‐coloured photochromic materials can open attractive perspectives for materials science applications.
Noémi Jordão; Pedro Ferreira; Hugo Cruz; A. Jorge Parola; Luís C. Branco. Photochromic Room Temperature Ionic Liquids Based on Anionic Diarylethene Derivatives. ChemPhotoChem 2019, 3, 525 -528.
AMA StyleNoémi Jordão, Pedro Ferreira, Hugo Cruz, A. Jorge Parola, Luís C. Branco. Photochromic Room Temperature Ionic Liquids Based on Anionic Diarylethene Derivatives. ChemPhotoChem. 2019; 3 (7):525-528.
Chicago/Turabian StyleNoémi Jordão; Pedro Ferreira; Hugo Cruz; A. Jorge Parola; Luís C. Branco. 2019. "Photochromic Room Temperature Ionic Liquids Based on Anionic Diarylethene Derivatives." ChemPhotoChem 3, no. 7: 525-528.
For the first time, 1,2-dimethyl-3-ethylimidazolium iodide (1a) catalyzes the ring opening of the bicyclic amidine system of DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) or DBN (1,5-diazabicyclo[4.3.0]non-5-ene) on reaction with aldehydes. The mechanism here proposed involves a N-heterocyclic olefin (NHO) catalytic species that acts as a nucleophile to promote the cyclic amidine ring opening. The resulting ε-caprolactam and γ-lactam-derived imines were obtained in moderate to excellent yields (28-99%) and reduced to the corresponding amines by sodium borohydride. Confirmation of the imine product was achieved via single crystal X-ray diffraction studies.
Daniela Peixoto; Gabriela Malta; Hugo Cruz; Sónia Barroso; Ana Luísa Carvalho; Luisa Maria Ferreira; Paula Serio Branco. N-Heterocyclic Olefin Catalysis for the Ring Opening of Cyclic Amidine Compounds: A Pathway to the Synthesis of ε-Caprolactam- and γ-Lactam-Derived Amines. The Journal of Organic Chemistry 2019, 84, 3793 -3800.
AMA StyleDaniela Peixoto, Gabriela Malta, Hugo Cruz, Sónia Barroso, Ana Luísa Carvalho, Luisa Maria Ferreira, Paula Serio Branco. N-Heterocyclic Olefin Catalysis for the Ring Opening of Cyclic Amidine Compounds: A Pathway to the Synthesis of ε-Caprolactam- and γ-Lactam-Derived Amines. The Journal of Organic Chemistry. 2019; 84 (7):3793-3800.
Chicago/Turabian StyleDaniela Peixoto; Gabriela Malta; Hugo Cruz; Sónia Barroso; Ana Luísa Carvalho; Luisa Maria Ferreira; Paula Serio Branco. 2019. "N-Heterocyclic Olefin Catalysis for the Ring Opening of Cyclic Amidine Compounds: A Pathway to the Synthesis of ε-Caprolactam- and γ-Lactam-Derived Amines." The Journal of Organic Chemistry 84, no. 7: 3793-3800.
Multi‐colored intrinsically electrochromic based Deep Eutectic Solvents (IEDES) have been firstly developed. IEDES composed by the suitable mixing between viologen salt derivatives as HBA and ethylene glycol (EG), glycerol (Gly) and poly(ethylene glycol) (PEG) as HBD have been prepared and characterized by thermal and electrochemical studies. A detailed electrochemical characterization of the IEDES using cyclic voltammetry studies in 2‐electrodes (ECDs) configuration cells were performed. The most promissory IEDES based on viologen salt derivatives can act simultaneously as electrolyte and electrochromic. Preliminary redox cycling studies showed a reversible and stable ECD composed by [(C5O2)2bpy]I2:EG at least until 1300 minutes. The coloration efficiency and reversibility can be tuned changing only the alcohol counterpart and/or the side chains and anion of the viologen derivatives. These IEDES can be explored as functional and efficient multi‐colored ECDs. Also, these innovative materials can open attractive applications for material science and energy devices.
Hugo Cruz; Noémi Jordão; Madalena Dionísio; Fernando Pina; Luís C. Branco. Intrinsically Electrochromic Deep Eutectic Solvents. ChemistrySelect 2019, 4, 1530 -1534.
AMA StyleHugo Cruz, Noémi Jordão, Madalena Dionísio, Fernando Pina, Luís C. Branco. Intrinsically Electrochromic Deep Eutectic Solvents. ChemistrySelect. 2019; 4 (4):1530-1534.
Chicago/Turabian StyleHugo Cruz; Noémi Jordão; Madalena Dionísio; Fernando Pina; Luís C. Branco. 2019. "Intrinsically Electrochromic Deep Eutectic Solvents." ChemistrySelect 4, no. 4: 1530-1534.
In this work, two bipyridinium di-cations based on [(allyl)2bpy]2+ and [(C10)2bpy]2+ combined with halogenate (I or Br), bistriflimide ([NTf2]) and dicyanamide [DCA] anions have been prepared and electrochemical characterized. These salts were studied using a conventional electrolyte (TBAP in acetonitrile) and alternative electrolyte based DES (LiTfO:6EG) for 3- and 2- electrodes configuration devices. In the 2-configuration device, [(allyl)2bpy][DCA]2 and [(C10)2bpy][DCA]2 showed different radical cation colorations particularly green and blue colors with different recovery times to original ones. In the case of [(C10)2bpy]I2 a blue and a red-violet colorations attributed to the electrogenerated radical cation and the dimer respectively was obtained in agreement with previous literature. In parallel, bipyridinium based DES by suitable combination between [(C10)2bpy]X2 and [(allyl)2bpy]X2 (X = Br, NTf2, DCA) with several hydrogen bond donors in 2-electrode configuration devices have been also studied. DES based on [(allyl)2bpy][NTf2]2:PEG200 and [(allyl)2bpy][DCA]2:PEG200 presented different coloration grades from pale brown to green taking longer times to recover the original color. The selected DES as alternative electrolytes or based bipyridinium derivatives can be promissory materials for efficient electrochromic devices.
Noémi Jordão; Hugo Cruz; Fernando Pina; Luís C. Branco. Studies of bipyridinium ionic liquids and deep eutectic solvents as electrolytes for electrochromic devices. Electrochimica Acta 2018, 283, 718 -726.
AMA StyleNoémi Jordão, Hugo Cruz, Fernando Pina, Luís C. Branco. Studies of bipyridinium ionic liquids and deep eutectic solvents as electrolytes for electrochromic devices. Electrochimica Acta. 2018; 283 ():718-726.
Chicago/Turabian StyleNoémi Jordão; Hugo Cruz; Fernando Pina; Luís C. Branco. 2018. "Studies of bipyridinium ionic liquids and deep eutectic solvents as electrolytes for electrochromic devices." Electrochimica Acta 283, no. : 718-726.
Deep Eutectic Solvents (DES) based on lithium and sodium combined with glycerol, ethylene glycol and polyethylene glycol (PEG400) as suitable electrolytes were developed and successfully applied in electrochromic devices (ECD). Reversible ECD incorporating selected DES as sustainable electrolyte and bipyridinium as electrochromic probes display a comparable performance than conventional systems.
Hugo Cruz; Noémi Jordão; Patrícia Amorim; Madalena Dionísio; Luís C. Branco. Deep Eutectic Solvents as Suitable Electrolytes for Electrochromic Devices. ACS Sustainable Chemistry & Engineering 2018, 6, 2240 -2249.
AMA StyleHugo Cruz, Noémi Jordão, Patrícia Amorim, Madalena Dionísio, Luís C. Branco. Deep Eutectic Solvents as Suitable Electrolytes for Electrochromic Devices. ACS Sustainable Chemistry & Engineering. 2018; 6 (2):2240-2249.
Chicago/Turabian StyleHugo Cruz; Noémi Jordão; Patrícia Amorim; Madalena Dionísio; Luís C. Branco. 2018. "Deep Eutectic Solvents as Suitable Electrolytes for Electrochromic Devices." ACS Sustainable Chemistry & Engineering 6, no. 2: 2240-2249.
Symmetrical and nonsymmetrical oxobis(bipyridinium) cations combined with iodide and bistriflimide anions were prepared. In the case of the bistriflimide-based bis(bipyridinium) salts, two room-temperature ionic liquids (RTILs) with a combination of linkers and terminal ethers, [(C3O)bpy(C4O)bpy(C3O)][NTf2]4 and [(C10)bpy(C4O)bpy(C3O)][NTf2]4, were obtained, with glass transition temperatures (between −6.9 and 6.0 °C) higher than those reported previously for salts of dication bipyridinium scaffolds (−17.5 to −30.0 °C). The prepared salt containing [(C10)bpy(C4O)bpy(C10)][NTf2] can form an ionic liquid crystal structure. The most promising salts were tested as efficient and reversible multicolored electrochromic devices through cyclic voltammetry studies and detailed characterizations of their electrochromic performances. In general, tetracations based on oxobis(bipyridinium) salts show higher chromatic contrast and lower coloration efficiency than similar dication salts. Exchange of the anion from iodide to [NTf2] increases the transition times and coloration efficiencies for all the prepared di- and tetracation salts. The electrochromic device stability of [(C3O)bpy(C4O)bpyC3O]I4 was tested by on/off cycling; this device loses around 23 % of the initial color after 8640 redox cycles and shows very good cycling stability compared with previously reported diiodide salts.
Noémi Jordão; Hugo Cruz; Aida Branco; Fernando Pina; Luís C. Branco. Bis(bipyridinium) Salts as Multicolored Electrochromic Devices. ChemPlusChem 2017, 82, 1211 -1217.
AMA StyleNoémi Jordão, Hugo Cruz, Aida Branco, Fernando Pina, Luís C. Branco. Bis(bipyridinium) Salts as Multicolored Electrochromic Devices. ChemPlusChem. 2017; 82 (9):1211-1217.
Chicago/Turabian StyleNoémi Jordão; Hugo Cruz; Aida Branco; Fernando Pina; Luís C. Branco. 2017. "Bis(bipyridinium) Salts as Multicolored Electrochromic Devices." ChemPlusChem 82, no. 9: 1211-1217.
The application of deep eutectic solvents based on choline chloride or lithium chloride with ethylene glycol and glycerol as low-cost, recyclable and green electrolytes for electrochromic devices is reported.
Hugo Cruz; Noémi Jordão; Luís C. Branco. Deep eutectic solvents (DESs) as low-cost and green electrolytes for electrochromic devices. Green Chemistry 2017, 19, 1653 -1658.
AMA StyleHugo Cruz, Noémi Jordão, Luís C. Branco. Deep eutectic solvents (DESs) as low-cost and green electrolytes for electrochromic devices. Green Chemistry. 2017; 19 (7):1653-1658.
Chicago/Turabian StyleHugo Cruz; Noémi Jordão; Luís C. Branco. 2017. "Deep eutectic solvents (DESs) as low-cost and green electrolytes for electrochromic devices." Green Chemistry 19, no. 7: 1653-1658.
An observable and reversible case of thermochromism due to an unusual interaction between the countercation and the ligand of an europium(iii) tetrakis-β-diketonate room temperature ionic liquid is reported.
Bernardo Monteiro; Mani Outis; Hugo Cruz; João Paulo Leal; César A. T. Laia; Cláudia C. L. Pereira. A thermochromic europium(iii) room temperature ionic liquid with thermally activated anion–cation interactions. Chemical Communications 2016, 53, 850 -853.
AMA StyleBernardo Monteiro, Mani Outis, Hugo Cruz, João Paulo Leal, César A. T. Laia, Cláudia C. L. Pereira. A thermochromic europium(iii) room temperature ionic liquid with thermally activated anion–cation interactions. Chemical Communications. 2016; 53 (5):850-853.
Chicago/Turabian StyleBernardo Monteiro; Mani Outis; Hugo Cruz; João Paulo Leal; César A. T. Laia; Cláudia C. L. Pereira. 2016. "A thermochromic europium(iii) room temperature ionic liquid with thermally activated anion–cation interactions." Chemical Communications 53, no. 5: 850-853.
Karolina Zalewska; Miguel M. Santos; Hugo Cruz; Luis C. Branco. Photo-Organocatalysis, Photo-Redox, and Electro- Organocatalysis Processes. Recent Advances in Organocatalysis 2016, 1 .
AMA StyleKarolina Zalewska, Miguel M. Santos, Hugo Cruz, Luis C. Branco. Photo-Organocatalysis, Photo-Redox, and Electro- Organocatalysis Processes. Recent Advances in Organocatalysis. 2016; ():1.
Chicago/Turabian StyleKarolina Zalewska; Miguel M. Santos; Hugo Cruz; Luis C. Branco. 2016. "Photo-Organocatalysis, Photo-Redox, and Electro- Organocatalysis Processes." Recent Advances in Organocatalysis , no. : 1.
A multistate molecular dyad containing flavylium and viologen units was synthesized and the pH dependent thermodynamics of the network completely characterized by a variety of spectroscopic techniques such as NMR, UV-vis and stopped-flow. The flavylium cation is only stable at acidic pH values. Above pH ≈ 5 the hydration of the flavylium leads to the formation of the hemiketal followed by ring-opening tautomerization to give the cis -chalcone. Finally, this last species isomerizes to give the trans -chalcone. For the present system only the flavylium cation and the trans -chalcone species could be detected as being thermodynamically stable. The hemiketal and the cis -chalcone are kinetic intermediates with negligible concentrations at the equilibrium. All stable species of the network were found to form 1 : 1 and 2 : 1 host : guest complexes with cucurbit[7]uril (CB7) with association constants in the ranges 10 5 –10 8 M −1 and 10 3 –10 4 M −1 , respectively. The 1 : 1 complexes were particularly interesting to devise pH responsive bistable pseudorotaxanes: at basic pH values (≈12) the flavylium cation interconverts into the deprotonated trans -chalcone in a few minutes and under these conditions the CB7 wheel was found to be located around the viologen unit. A decrease in pH to values around 1 regenerates the flavylium cation in seconds and the macrocycle is translocated to the middle of the axle. On the other hand, if the pH is decreased to 6, the deprotonated trans -chalcone is neutralized to give a metastable species that evolves to the thermodynamically stable flavylium cation in ca. 20 hours. By taking advantage of the pH-dependent kinetics of the trans -chalcone/flavylium interconversion, spatiotemporal control of the molecular organization in pseudorotaxane systems can be achieved.
Ana Marta Diniz; Nuno Basílio; Hugo Cruz; Fernando Pina; A. Jorge Parola. Spatiotemporal control over the co-conformational switching in pH-responsive flavylium-based multistate pseudorotaxanes. Faraday Discussions 2015, 185, 361 -379.
AMA StyleAna Marta Diniz, Nuno Basílio, Hugo Cruz, Fernando Pina, A. Jorge Parola. Spatiotemporal control over the co-conformational switching in pH-responsive flavylium-based multistate pseudorotaxanes. Faraday Discussions. 2015; 185 ():361-379.
Chicago/Turabian StyleAna Marta Diniz; Nuno Basílio; Hugo Cruz; Fernando Pina; A. Jorge Parola. 2015. "Spatiotemporal control over the co-conformational switching in pH-responsive flavylium-based multistate pseudorotaxanes." Faraday Discussions 185, no. : 361-379.
Gel switchable electrochromic devices based on disubstituted bipyridinium derivatives have been developed.
Noémi Jordão; Hugo Cruz; Aida Branco; Carlos Pinheiro; Fernando Pina; Luís C. Branco. Switchable electrochromic devices based on disubstituted bipyridinium derivatives. RSC Advances 2015, 5, 27867 -27873.
AMA StyleNoémi Jordão, Hugo Cruz, Aida Branco, Carlos Pinheiro, Fernando Pina, Luís C. Branco. Switchable electrochromic devices based on disubstituted bipyridinium derivatives. RSC Advances. 2015; 5 (35):27867-27873.
Chicago/Turabian StyleNoémi Jordão; Hugo Cruz; Aida Branco; Carlos Pinheiro; Fernando Pina; Luís C. Branco. 2015. "Switchable electrochromic devices based on disubstituted bipyridinium derivatives." RSC Advances 5, no. 35: 27867-27873.
Primary alkyl amines are one of the most commonly used and effective reagents in CO2 capture. Most of the amines used for CO2 capture are recycled, but a minor portion of the amines are degraded after one electron oxidation process, leading to highly toxic substances. The combination of the complementary information obtained from photoinduced electron transfer (flash photolysis) and heterogeneous electron transfer (electrochemistry) appears to be very attractive to fully characterize the electron transfer reaction mechanism of reactive species in general, as well as for determining important thermodynamic properties, such as standard potentials (E°) or pKa values. It is particularly difficult to determine these crucial data accurately in the cases of alkyl primary amines. Hence, in this manuscript we focus on the establishment of the several alkyl primary amines oxidation mechanism in organic aprotic solvents. In order to achieve this, this work combines information provided by flash photolysis (nanosecond), cyclic voltammetry (millisecond), and digital simulation (nanomile-second). Moreover, the accuracy of the E° values calculated using the nanosecond equilibrium method allows not only revising them, but also estimating new important thermodynamic data concerning the bond dissociation energies (BDEs) of ammonium cations (N+–H) and of the amine cation radicals (α-C–H), as well as their corresponding pKa values.
Hugo Cruz; Jose Luis Bourdelande; Iluminada Gallardo; Gonzalo Guirado. Combining Nanosecond and Millisecond Time Scale Techniques: Determination of Thermodynamic and Kinetic data of Primary Alkyl Amine Cation Radicals. The Journal of Physical Chemistry A 2015, 119, 620 -633.
AMA StyleHugo Cruz, Jose Luis Bourdelande, Iluminada Gallardo, Gonzalo Guirado. Combining Nanosecond and Millisecond Time Scale Techniques: Determination of Thermodynamic and Kinetic data of Primary Alkyl Amine Cation Radicals. The Journal of Physical Chemistry A. 2015; 119 (4):620-633.
Chicago/Turabian StyleHugo Cruz; Jose Luis Bourdelande; Iluminada Gallardo; Gonzalo Guirado. 2015. "Combining Nanosecond and Millisecond Time Scale Techniques: Determination of Thermodynamic and Kinetic data of Primary Alkyl Amine Cation Radicals." The Journal of Physical Chemistry A 119, no. 4: 620-633.
Electrochromic symmetric and non‐symmetric disubstituted oxo‐bipyridinium ionic liquids are developed in high purities and yields. Detailed spectroscopic (NMR, FTIR and elemental analysis), thermal (DSC for melting point and glass transition temperatures, Tg determination) and electrochemical (cyclic and square wave voltammetry for determination of redox potential and evaluation of reversibility behaviour) analyses are performed. The most promising electrochromic oxo‐bipyridinium ionic liquids in combination with transparent electrolytes are tested as reversible electrochromic devices. More efficient and sustainable electrochromic devices inspired by bipyridinium ionic liquids can be conceived for industrial applications such as electrochromic car rear‐view mirrors and smart windows.
Noémi Jordão; Hugo Cruz; Aida Branco; Fernando Pina; Luis C. Branco. Electrochromic Devices Based on Disubstituted Oxo-Bipyridinium Ionic Liquids. ChemPlusChem 2014, 80, 202 -208.
AMA StyleNoémi Jordão, Hugo Cruz, Aida Branco, Fernando Pina, Luis C. Branco. Electrochromic Devices Based on Disubstituted Oxo-Bipyridinium Ionic Liquids. ChemPlusChem. 2014; 80 (1):202-208.
Chicago/Turabian StyleNoémi Jordão; Hugo Cruz; Aida Branco; Fernando Pina; Luis C. Branco. 2014. "Electrochromic Devices Based on Disubstituted Oxo-Bipyridinium Ionic Liquids." ChemPlusChem 80, no. 1: 202-208.
Using in situ viscosity measurement, the rate of cellulose dissolution in a number of ionic liquids has been determined allowing their performance as solvents to be quantitatively assessed. 1-Butyl-3-methylimidazolium ethanoate was shown to dissolve cellulose faster than analogous ionic liquids with chloride or dimethylphosphate anions. Analysis of the data highlights the influence of both anion basicity and relative concentration on the rate of dissolution.
Hugo Cruz; Markus Fanselow; John Holbrey; Kenneth R. Seddon. Determining relative rates of cellulose dissolution in ionic liquids through in situ viscosity measurement. Chemical Communications 2012, 48, 5620 .
AMA StyleHugo Cruz, Markus Fanselow, John Holbrey, Kenneth R. Seddon. Determining relative rates of cellulose dissolution in ionic liquids through in situ viscosity measurement. Chemical Communications. 2012; 48 (45):5620.
Chicago/Turabian StyleHugo Cruz; Markus Fanselow; John Holbrey; Kenneth R. Seddon. 2012. "Determining relative rates of cellulose dissolution in ionic liquids through in situ viscosity measurement." Chemical Communications 48, no. 45: 5620.