The dataset shows the experimental data provided in the main text and supporting information of the article "Enhanced Electrochromic Smart Windows Based on Supramolecular Viologen Tweezers": NMR data, absorption and transmittance spectra, cyclic voltamogramms, impedance measurements, spectroelectrochemical measurements and temperature variation into house models upon sunlight irradiation.

Universitat Autònoma de Barcelona. Grup d’Electroquímica, Fotoquímica i Reactivitat Orgànica (GEFRO).

• Description of methods used for collection-generation of data:

The NMR spectrum of 2V-PF6 was registered in a Bruker Avance III™ HD 500 MHz spectrometer in CD3CN. The electronic absorption of the compounds in acetonitrile solution were recorded on an Agilent Cary 5000 spectrophotometer with a PbSmart NIR detector. For the reduced species, samples were prepared by dissolving the compounds of interest in oxygen-degassed acetonitrile and mixing them with Zn powder in a glovebox. After 30 minutes under gentile stirring, the mixture was filtrated using 0.2 µm syringe filters and placed into a UV-Vis cuvette with a septum cap. Then, the sample was taken out from the glovebox and the absorption spectra were immediately measured. The absorption spectra of the compounds in ionic liquids and ionogels was acquired using a Hamamatsu L10290 spectrophotometer. When needed, a potential was applied using a VSP100 potentiostat controlled by EC-Lab V9.51 software and coupled to the Hamamatsu L10290 spectrophotometer. Electrochemical measurements in liquid solution (ACN/0.1 M TBA PF6 or ionic liquid) were performed with a VSP100 potentiostat in a conical cell using a 1-mm in diameter glassy carbon disk as a working electrode, a Pt disk (diameter < 1 mm) as a counter electrode, and a standard Ag/AgCl reference electrode. The salt solution of the reference Ag/AgCl electrode was separated from the electrochemical solution by a salt-bridge ended with a frit, which was made of a ceramic material, allowing ionic conduction between the two solutions and avoiding appreciable contamination. The electrolyte solution present in the bridge was the same as the one used for the electrochemical solution, to minimize junction potentials. The error associated with the potential values is less than 5 mV. The ohmic drop can be one of the main sources of error when ILs are used as solvents, since they are more resistive media than aprotic polar solvents with 0.1 M concentration of supporting electrolyte. Spectroelectrochemical measurements in liquid solution (ACN/0.1 M TBA PF6 or ionic liquid) were performed in a 1 mm-optical path quartz cuvette using a Pt grid as a working electrode, a Pt wire as counter electrode and a Ag/AgCl as a reference electrode. All these experiments in solution were performed after degassing with an inert gas (N2 or Ar) for 10 min. Electrochemical and spectroelectrochemical measurements of the ionogels containing the viologen compounds were performed using screen-printed electrodes (SPE, DropSens), a three-electrode system composed of a carbon or an optically-transparent ITO working electrode, a carbon counter electrode, and an Ag pseudo-reference electrode. The absorption and transmittance measurements of the electrochromic devices were obtained using an Agilent Cary 60 spectrophotometer, and a power supply was utilized to deliver the desired potential to the device. The stability of the electrochromic devices under 950 switching cycles was performed with the Hamamatsu L10290 spectrophotometer coupled to the VSP100 potentiostat controlled by EC-Lab V9.51 software. The energy-saving experiments were performed using an insulating polystyrene box as a house model with (i) a small aperture (2.5 cm x 2.5 cm) in the top covered with the electrochromic device, and (ii) a lateral aperture (5 cm x 5 cm) where the IR thermographic camera Uni-T UTi712S was placed to monitor the temperature. The box was irradiated through the small upper aperture using a solar simulator (Abet SunLite™ 11002, AM1.5G filter) at 100 mW cm-2. The morphology of the IGs was characterized by means of confocal imaging as a non-contact optical 3D profiling technique using the DCM 3D optical profilometer (Leica) provided by the UAB Microscopy Service. AC impedance spectroscopy measurements were recorded using a 1287 potentiostat controlled by Zplot 3.5i software coupled with an electrochemical interface for frequency response analyzer (FRA, 1260A Impedance Analyzer).

• Methods for processing the data: The data was either obtained directly from the instrument software in csv format or readed analogically and writed in the notebook. All ASCII data was plotyed using Origin.

• Instruments, calibration and standards information: Bruker Avance III™ HD 500 MHz, Agilent Cary 60, Agilent Cary 5000 and Hamamatsu L10290 spectrophotometer; VSP100 potentiostat; IR thermographic camera Uni-T UTi712S, bet SunLite™ 11002, AM1.5G filter solar simulator, FRA, 1260A Impedance Analyzer.

• Environmental or experimental conditions: Experiments conducted at atmospheric pressure, controled temperatures and controled athmosphere.

• Quality-assurance procedures performed on the data: No.