pyrazole-thermal synthesis: new approach towards n-rich ... · electronic supplementary material...

Electronic Supplementary Material (ESI) for Dalton Transactions This journal is © The Royal Society of Chemistry 2019

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Supporting Information for:

Pyrazole-thermal Synthesis: New Approach towards N-Rich

Titanium-Oxo Clusters with Photochromic Behaviors

Xi Fanab, Hao Fuab, Lei Zhanga* and Jian Zhanga

a. State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China. b. University of Chinese Academy of Sciences, 100049 Beijing, China. Corresponding Author E-mail: [email protected]

Electronic Supplementary Material (ESI) for Dalton Transactions.This journal is © The Royal Society of Chemistry 2019

mailto:[email protected]


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Experimental Section

Materials and Instrumentation. We collected the Fourier transform infrared spectroscopy (FTIR) data on a

PerkinElmer Spectrum 100 FT-IR Spectrometer. Thermogravimetric analyses (TGA) were performed on a Mettler

Toledo TGA/SDTA 851e analyzer in N2 with a heating rate of 10 oC min-1 from 20 oC to 800 oC. Powder X-ray

diffraction (PXRD) data analysis were collected on a Rigaku Mini Flex II diffractometer using CuKα radiation (λ

=1.54056 Å) in the 2θ range of 5–50° with a scanning rate of 5° min−1. The UV diffuse reflection data were

recorded at room temperature using a powder sample with BaSO4 as a standard (100% reflectance) on a

PerkinElmer Lamda-950 UV spectrophotometer and scanned at 200-800 nm. The absorption data are calculated

from the Kubelka-Munk function, (F(R) = (1-R)2/2R), where R representing the reflectance. A 300 W Xe lamp was

used as the UV-vis light source to prepare samples for Electron Paramagnetic Resonance (EPR). EPR spectra were

recorded on a Bruker ER-420 spectrometer with a 100 kHz magnetic field at room temperature.

Chemicals and Materials

All the reagents and solvents were purchased commercially and were not further purified when used. Pyrazole,

catechol, 1,2,4-triazole and Ti(OiPr)4 were purchased from Adamas, while pyridine were bought from Sino pharm

Chemical Reagent Beijing.

Synthesis of PTC-195: Catechol (0.33 g, 3 mmol) and pyrazole (2.0 g) were mixed at room temperature, then

Ti(OiPr)4 (0.92 ml, 3.0 mmol) was added. The resultant mixture was heated at 100 °C for 1 day. After cooled to

room temperature, the mixture was washed by isopropanol and red crystals of PTC-195 were obtained (yield:

53% based on Ti(OiPr)4). Elemental analysis for C54H68N12O14Ti4, Calcd (%): C, 49.87; H, 5.27; N, 12.92. Found:

C, 49.59; H, 5.34; N, 12.68. IR data : 2973(w), 2929(w), 2864(w), 1572(w), 1476(s), 1401(m), 1377(w),

1358(m), 1325(w), 1251(s), 1210(w), 1166(s), 1118(s), 1064(s), 1049(w), 1012(s), 942(w), 803(m), 766(m),

733(s),614(s).

Synthesis of PTC-196: 1,2,4-Triazole (0.10 g, 1.45 mmol) and pyrazole (2.0 g) were mixed at room temperature,

then Ti(OiPr)4 (0.92 ml, 3.0 mmol) was added. The resultant mixture was heated at 100 °C for 6 hours. After

cooled to room temperature, the mixture was washed by isopropanol and colorless crystals of PTC-196 were

obtained (yield: 26% based on Ti(OiPr)4). Elemental analysis for C58H114N14O16Ti6, Calcd (%): C, 44.92; H, 7.41;

N, 12.64. Found: C, 45.23; H, 7.38; N, 12.32. IR data : 2965(w), 2926(w), 2856(w), 1503(w), 1484(w),

1415(w), 1369(m), 1323(w), 1267(w), 1119(s), 1073(w), 1047(m), 1001(s), 982(s), 877(w), 849(s), 756(s),

667(m), 625(s).

Synthesis of PTC-197: Pyridine (0.10 g, 1.26 mmol) and pyrazole (2.0 g) were mixed at room temperature, then

Ti(OiPr)4 (0.92 ml, 3.0 mmol) was added. The resultant mixture was heated at 100 °C for 1 day. After cooled to

room temperature, the mixture was washed by isopropanol and colorless crystals of PTC-197 were obtained

(yield: 65% based on Ti(OiPr)4). Elemental analysis for C60H96N24O20Ti10, Calcd (%): C, 36.91; H, 4.96; N, 17.22.


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Found: C, 36.89; H, 4.74; N, 17.43. IR data : 2955(w), 2921(w), 2855(w), 1546(w), 1485(m), 1459(w),

1412(w), 1360(s), 1325(w), 1270(s), 1156(s), 1119(s), 1037(s), 1058(w), 1043(s), 1014(w), 970(m), 843(m),

744(s), 635(s).

Photochromic Experiment: Typically, 200 mg of sample was added into 100 mL 10% methanol aqueous

solution tube at 5℃connected with circulating condensing system. The mixture was illuminated under

UV-vis light until the color of the mixture turned to black purple. Then, the liquid part was removed and the

remaining solid sample was used for EPR measurements at room temperature immediately.

General Methods for X-ray Crystallography. The structure determination of PTC-195 was performed at 293(K)

on the Saturn 724+ diffractometer using graphite-monochromated Mo-K radiation. Crystallographic data of

complexes PTC-196 and PTC-197 were collected on a Supernova single crystal diffractometer equipped with

graphite-monochromatic CuK radiation (λ = 1.54178 Å) at 100 K. The structure was solved with direct methods

using SHELXS-2014 and refined with the full-matrix least-squares technique based on F2 using the SHELXL-2014.

Non-hydrogen atoms were refined anisotropically, and all hydrogen atoms bond C were generated

geometrically.

Table S1. Crystallographic Data and Structure Refinement Details for PTC-195 to PTC-197.

Compounds PTC-195 PTC-196 PTC-197

Empirical formula C26H34N7O7Ti2 C29H57N7O8Ti3 C60H96N24O20Ti10 Formula weight 652.40 775.51 1952.60 Temperature/K 293(2) 100.00(15) 295.56(10) Crystal system triclinic monoclinic triclinic Space group P-1 P21/n P-1 a/Å 11.235(5) 12.7979(6) 13.7282(4) b/Å 11.733(5) 23.8477(14) 14.6322(3) c/Å 12.526(6) 13.0520(7) 23.1079(6) α/° 101.117(4) 90 93.789(2) β/° 96.655(8) 98.629(5) 99.033(2) γ/° 98.380(5) 90 104.107(2) Volume/Å

3 1585.3(12) 3938.4(4) 4419.5(2)

Z 2 4 2

ρcalcg/cm3 1.367 1.308 1.467

μ/mm-1

0.556 5.483 7.905 F(000) 678.0 1640.0 2008.0 Radiation MoKα (λ = 0.71073) CuKα (λ = 1.54184) CuKα (λ = 1.54184)

Index ranges -13 ≤ h ≤ 12, -15 ≤ k ≤ 15, -16 ≤ l ≤ 16

-15 ≤ h ≤ 14, -29 ≤ k ≤ 20, -15 ≤ l ≤ 14

-16 ≤ h ≤ 15, -17 ≤ k ≤ 15, -27 ≤ l ≤ 27

Reflections collected 12496 16294 31097

Independent reflections 6842 [Rint = 0.0200, Rsigma = 0.0286]

7129 [Rint = 0.0887, Rsigma = 0.1046]

16568 [Rint = 0.0471, Rsigma = 0.0568]

Data/restraints/parameters 6842/0/375 7129/0/438 16568/3/1064 Goodness-of-fit on F

2 1.059 1.038 1.037

Final R indexes *I>=2σ (I)+ R1 = 0.0586, wR2 = 0.1859 R1 = 0.0829, wR2 = 0.2072 R1 = 0.0532, wR2 = 0.1406 Final R indexes [all data] R1 = 0.0680, wR2 = 0.1951 R1 = 0.1118, wR2 = 0.2411 R1 = 0.0628, wR2 = 0.1537 Largest diff. peak/hole / e Å

-3 0.62/-0.65 0.91/-0.58 0.46/-1.04


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Figure S1. Packing diagram of PTC-195 in the view of (a) a-axis, (b) b-axis and (c) c-axis.




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Figure S4. Illustration of strong intramolecular hydrogen bonds between the uncoordinated N-H of terminated

pyrazole and oxygen in the cluster of PTC-197.

Figure S5. Experimental and simulated powder X-Ray diffraction patterns for PTC-195.


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Figure S6. The PXRD patterns of simulation, original crystals and retrieved samples after photochromic tests of PTC-196.

Figure S7. The PXRD patterns of simulation, original crystals and retrieved samples after photochromic

tests of PTC-197.


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Figure S8. The IR spectrum of PTC-195. IR spectra for the crystals shows apparent absorption bands in the range of 1250–1500 cm-1 corresponding to catechol stretching. The absorption bands in the range of 1000–1200 cm-1

should be assigned to pyrazole stretching. The formation of Ti-O bond can also be confirmed through the strong peaks observed at approximately 500-800 cm-1.

Figure S9. The IR spectrum of original crystals and retrieved samples after photochromic tests of PTC-196. IR spectra for the crystals shows apparent absorption bands in the range of 1000–1200 cm-1 corresponding to

pyrazole and triazole stretching. The formation of Ti-O bond can also be confirmed through the strong peaks observed at approximately 500-800 cm-1.


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Figure S10. The IR spectrum of original crystals and retrieved samples after photochromic tests of PTC-197. IR spectra for the crystals shows apparent absorption bands in the range of 1000–1200 cm-1 corresponding to

pyrazole stretching. The formation of Ti-O bond can also be confirmed through the strong peaks observed at approximately 500-800 cm-1.

Figure S11. The TGA curve of PTC-195.


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Figure S14. Illustration the crystals photo of PTC-196 before and after irradiation. The slight color change is

irreversible.

Figure S15. Illustration the reversible photochromic transformation of PTC-197 by alternating UV irradiation and

air exposure or heating.

Figure S16. ESR spectra of retrieved samples after photochromic tests of PTC-196.


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Figure S17. The Solid state UV-vis absorption spectra of original crystals and retrieved samples after

photochromic tests of PTC-196.

Figure S18. Diffraction image (SuperNova) of the single crystal of PTC-196 after photochromic experiment.

Single-crystal X-ray diffraction analysis reveals that retrieved crystal was still the original structure, fully confirmed the stability of PTC-196 during the photochromic experiment.

Figure S19. Diffraction image (SuperNova) of the single crystal of PTC-197 after photochromic experiment.

Single-crystal X-ray diffraction analysis reveals that retrieved crystal was still the original structure, fully confirmed the stability of PTC-197 during the photochromic experiment.

pyrazole-thermal synthesis: new approach towards n-rich ... · electronic supplementary material...

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