A stimuli responsive Au ( I ) complex based on aminomethylphosphine template : synthesis , crystalline phases and luminescent properties

Herein we report the synthesis of a stimuli-responsive binuclear Au(I) complex based on the 1,5-bis(p-tolyl)-3,7-bis(pyridine-2-yl)-1,5-diaza-3,7-diphosphacyclooctane ligand, which is a novel template for the design of luminescent metal complexes. In the solid state, the complex obtained gives three different crystalline phases, which were characterized by XRD analysis. It was also found that the crystalline phases can be reversibly interconverted by recrystallization or solvent vapour treatment. The emission of these phases varies in the 500–535 nm range. Quite unexpectedly, the emission energy of these phases is mostly determined by the non-covalent interactions of the solvent molecules with the ligand environment, which have nearly no effect on the Au–Au interactions in the chromophoric centre. The complex obtained demonstrates thermo/solvatochromism to display greenish emission in a DCM matrix and blue emission in an acetone matrix at 77 K, in contrast to the blue emission of the phase containing a DCM molecule and greenish-yellow emission of the acetone solvate in a crystal cell at room temperature. The potentially important role of co-crystallized solvent molecules in the ligand-based emission of the complex obtained is supported by DFT calculations.


Crystalline phases transformation
Crystallography data for 1a-c       Table S1.Crystallographic data for 1.

Computational details
Table S2.PXRD data for the crystalline phase 1a.Table S3.PXRD data for the crystalline phase 1b.
Table S4.PXRD data for the crystalline phase 1c.

Crystalline phases transformation
Recrystallization.The phase 1a was obtained by the recrystallization of obtained dry powder of 1 from dichloromethane (DCM).The phase 1b was obtained by the recrystallization of 1a from acetone.The recrystallization of 1a or 1b from the mixture of DCM/acetone gives the phase 1c.
The phase 1b was also obtained by the recrystallization of 1c from pure acetone while 1a resulted due to the recrystallization of 1b−c from pure DCM.
Vapors treatment.The treatment of the powders of 1a and 1c with acetone vapors results in changing the color of emission to that of 1b.The treatment of 1b with the vapors of DCM returns the color of emission to that of 1a.

Crystallographic data for 1a-c
Single crystals of 1 suitable for X-ray analysis were grown from dichloromethane (1a), from acetone (1b), from acetone/dichloromethane mixture (1c).Single crystals of 1c were also grown after careful recrystallization of 1b from acetone/dichloromethane mixture.
Crystal structures of 1a, 1b and 1c were determined by the means of single crystal X-ray diffraction analysis.Crystal of 1a was fixed on a micro mount, placed on Rigaku Oxford Diffraction Supernova Atlas diffractometer and measured at a temperature of 100K using microfocused monochromated CuKα radiation.Crystals of 1b and 1c were fixed on a micro mounts, placed on a Rigaku Oxford Diffraction Excalibur Eos diffractometer and measured at a temperature of 100K using monochromated MoKα radiation.The unit cell parameters and refinement characteristics for the crystal structures of 1a -1c are given in the Table S1.The unit cell parameters of 1a were determined and refined by the least-squares techniques on the basis of 25914 reflections with 2θ in the range of 6.23-152.23°.From the systematic absences and statistics of reflection distribution, the space group P2/c was determined.The structure was solved by direct methods and refined to R1 = 0.044 (wR2 = 0.109) for 3895 reflections with |Fo| ≥ 4σF using the SHELXL-97 program2 F 3 incorporated in the OLEX2 program package.3F 4 The unit cell parameters of 1b were determined and refined by the least-squares techniques on the basis of 13247 reflections with 2θ in the range of 5.99-54.99°.From the systematic absences and statistics of reflection distribution, the space group P2/c was determined.The structure was solved by direct methods and refined to R1 = 0.026 (wR2 = 0.047) for 3217 reflections with |Fo| ≥ 4σF using the SHELXL-97 program 3 incorporated in the OLEX2 program package. 4 The unit cell parameters of 1c were determined and refined by the leastsquares techniques on the basis of 10227 reflections with 2θ in the range of 5.66-51.99°.From the systematic absences and statistics of reflection distribution, the space group C2/m was determined.
The structure was solved by direct methods and refined to R1 = 0.035 (wR2 = 0.082) for 3325 Geometry optimizations were performed for free PNNP ligand and complex 1, using one or two acetone molecules to model the environment of the complex in 1b and 1c phases.However, since the acetone molecules in 1b and 1c are not coordinated ligands, full geometry optimizations for these species did not result in structures resembling those obtained from XRD.In order to obtain a more realistic computational representation of structures of the complexes studied in this work,

Figure
Figure S1. 1 H NMR spectra of 1 in CDCl3 solution at room temperature.

Figure S5 .
Figure S5.Highest occupied and lowest vacant molecular orbitals for complex 1 without acetone molecules.

Figure S6 .
Figure S6.Highest occupied and lowest vacant molecular orbitals for complex 1 with two acetone molecules.Solvent molecules are fixed at their crystallographic positions in 1b phase.

Figure S7 .
Figure S7.Highest occupied and lowest vacant molecular orbitals for complex 1 with one acetone molecule.Solvent molecule is fixed at its crystallographic position in 1c phase.
used constrained geometry optimizations in which Au and P atoms, as well as C and O the atoms constituting the CO group in acetone molecules, were fixed at their crystallographic positions.Such calculations were carried out for the ground singlet states of complex 1 without acetone molecules (model of 1a phase), with two acetone molecules (1b), and with one acetone molecule (1c).The excited states of the species under investigation were further studied by timedependent DFT (TDDFT) calculations.

Figure S1. 1 H
Figure S1. 1 H NMR spectra of 1 in CDCl3 solution at room temperature.
The final models included coordinates and anisotropic displacement parameters for all non-hydrogen atoms.The carbon-bound H atoms were placed in calculated positions and were included in the refinement in the 'riding' model approximation, with Uiso(H) set to 1.5Ueq(C) and C-H 0.96 Å for the CH3 groups, Uiso(H) set to 1.2Ueq(C) and C-H 0.97 Å for the CH2 groups, 3 G.M. Sheldrick, Acta Cryst., 2008, A64, 112. 4 O.V. Dolomanov, L.J. Bourhis, R.J. Gildea, J.A.K. Howard, H. Puschmann, J. Appl.Cryst., 2009, 42, 339.S5 reflections with |Fo| ≥ 4σF using the SHELXL-97 program 3 incorporated in the OLEX2 program package. 4 F 6 The unit cell of 1a•3CH2Cl2 contains disordered dichloromethane molecules that have been treated as a diffuse contribution to the overall scattering without specific atom positions by SQUEEZE/PLATON. 7The total approximate amount of solvent molecules in the structural model of 1a has been calculated taking into account the Electron Count of 283 and a Total Potential Solvent Accessible Void Volume of 589.4 e/Å 3 .Supplementary crystallographic data for this paper have been deposited at Cambridge Crystallographic Data Centre (CCDC 1030853, 1027244 and 1027245 for 1a, 1b and 1c, respectively) and can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif.

Table S3 .
PXRD data for the crystalline phase 1b.

Table S4 .
PXRD data for the crystalline phase 1c.