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Article

A Pt(II) Complex with a PNN Type Ligand Dppmaphen Exhibits Selective, Reversible Vapor-Chromic Photoluminescence

by
Yuanyuan Hu
1,
Jiangyue Wang
1,
David James Young
2,
Hong-Xi Li
1,
Yuxin Lu
1,* and
Zhi-Gang Ren
1,*
1
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
2
James Watt School of Engineering, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK
*
Authors to whom correspondence should be addressed.
Inorganics 2025, 13(5), 170; https://doi.org/10.3390/inorganics13050170
Submission received: 25 April 2025 / Revised: 10 May 2025 / Accepted: 15 May 2025 / Published: 16 May 2025
(This article belongs to the Special Issue Editorial Board Members’ Collection Series in “Featuring Ligands and Their Applications in Coordination Chemistry”, 2nd Edition)
Browse Figures
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Abstract

:
The reaction of PtCl2 with a PNN type ligand dppmaphen (N-(diphenylphosphanylmethyl)-2-amino-1,10-phenanthroline) yielded a new Pt(II) complex [Pt(dppmaphen)Cl]Cl·H2O (1). Upon excitation at 370 nm, compound 1 emits yellow phosphorescence at 539 and 576 nm at room temperature. Exposure of compound 1 to MeOH vapor induces a shift in its emission to 645 nm, which can be attributed to the substitution of MeOH molecules for H2O, resulting in the disruption and reorganization of weak interactions in 1. This response is selective for MeOH and, to a lesser extent, EtOH, the orange photoluminescence recovered in air. The emission change of 1 was reversible and visible to the naked eye.

Graphical Abstract

1. Introduction

During the past decades, photoluminescent (PL) Pt(II) complexes have been extensively investigated for their potential applications as sensors [1,2,3,4], organic light-emitting diodes (OLEDs) [5,6,7,8,9], and biomedical materials [10,11,12,13,14,15]. Pt(II) centers commonly adopt square-planar tetracoordinate configurations, and this relatively planar geometry facilitates the stacking of solid-state Pt(II) complexes through intermolecular noncovalent interactions (e.g., Pt∙∙∙Pt interactions, π−π stacking, and hydrogen bonds) to give aggregates [16,17,18,19,20] with altered PL behavior.
The PL of Pt(II) complexes can be highly responsive to external stimuli such as temperature [21,22,23], solvents [24,25,26], vapors [27,28,29,30], and mechanical forces [31,32,33,34] which provide additional means of modulation for the design of novel luminescent materials with tunable emissions. For example, Kato et al. reported a Pt(II) complex [Pt(CN)2(H4dpbpy)], whose corresponding pentahydrated form exhibited a unique bidirectional vapor-induced color-changing PL triggered by two distinct desiccation conditions [35]. Similarly, Yang’s group developed a Pt(II)-based supramolecular metallacycle that exhibited reversible solid-state emission color switching between yellow and red upon exposure to CH2Cl2 vapor or mechanical grinding [36].
Recently, we have developed a number of phosphine-ligand-protected Au/Ag/Cu complexes with stimuli-responsive PL properties [37,38,39], which prompted us to further explore new PL Pt(II) complexes with different phosphine ligands to achieve novel stimuli-responsive materials. The PNN-type ligand dppmaphen [39] contains a −PPh2 group, a 1,10-phenanthroline (−phen) group, and a −NH− group, offering multiple binding sites not only for coordinating with metal centers [40,41,42], but also capable of weak interactions including π−π stacking and hydrogen bonds that influence the PL of its Pt(II) complexes. Herein, we report the synthesis and structure of a new complex [Pt(dppmaphen)Cl]Cl∙H2O (1) obtained from the reaction of dppmaphen with PtCl2, and its selective and reversible vapor-chromic PL responsive to MeOH.

2. Results and Discussion

2.1. Synthesis and Characterization

The reaction of equimolar PtCl₂ and dppmaphen in DMSO/MeCN afforded a yellow precipitate, which was recrystallized from EtOH/CH₂Cl₂ (1:5, v/v) and n-hexane to give yellow crystals of complex 1 after 10 days in a yield of 22% (Scheme 1).
Complex 1 was insoluble in H2O, THF, MeCN, and acetone, and soluble in MeOH, EtOH, CH2Cl2, CHCl3, DMSO, and DMF. The IR spectrum of 1 (Figure S1) contained characteristic absorbances for −Ph and −phen at 1632, 1563, and 1440 cm−1. The 1H NMR (in DMSO-d6, Figure S2) spectrum contained signals for −CH₂− (4.74 ppm), −NH− (7.41 ppm), −Ph and −phen (9.88–7.58 ppm). The 31P{1H} NMR spectrum consisted of a signal centered at −1.07 ppm attributed to −PPh2. Thermogravimetric analysis (TGA) of 1 in a N2 stream (Figure S3) showed a weight loss of 2.3% in the range 80–115 °C, consistent with the loss of one H2O molecule (calcd. 2.7%).
Single-crystal X-ray diffraction (SCXRD) analysis of 1 at 223 K revealed that it crystallized in the triclinic Pī space group. The asymmetric unit contained one [Pt(dppmaphen)Cl]+ cation, one Cl− anion, and one H2O molecule. As shown in Figure 1, the central Pt(II) atom was coordinated in a planar square configuration with two N atoms and one P atom from the ligand dppmaphen, as well as one Cl− anion. The shortest intermolecular Pt···Pt distance was 7.303 Å, precluding any Pt···Pt interactions.

2.2. Photophysical Properties of 1

As shown in Figure 2a, under 370 nm excitation, compound 1 exhibited a structured high-energy (HE) emission band at 539 nm and 576 nm in the solid state at room temperature. A weak shouldered peak at around 630 nm was also observed. The excitation spectra of 1 showed negligible changes when the emission wavelength was varied between 539 and 576 nm. The nearly identical PL lifetimes of the two emission peaks (τ = 5.5 μs at 539 nm and 5.8 μs at 576 nm) indicated that they originate from one single emission source. The microsecond range lifetimes suggested that this HE band can be assigned to phosphorescence. The total quantum yield (QY) of the emission was 1.23%, which was observed as a bright yellow PL (Figure 2b).
Density functional theory (DFT) calculations based on the cationic structure of 1 (Figure 3) revealed that the lowest unoccupied molecular orbitals (LUMO and LUMO+1) were localized at the π* orbitals of the –phen group. The highest occupied molecular orbital (HOMO) was primarily distributed in the 5d orbitals of the Pt atom, 3p orbitals of the Cl atom and π orbitals of the –phen group, while the HOMO-1 was mainly localized at the 5d orbitals of the Pt atom, 3p orbitals of the Cl atom and π orbitals of the −Ph groups. Consequently, the PL of 1 can be attributed to a metal–ligand–ligand charge transfer (3MLLCT) [43,44] mixed with metal-mediated ligand-to-ligand charge transfer (3LLCT) [45,46,47].
We further investigated the temperature-dependent emission spectra of 1. As shown in Figure 4, the intensity of the emission band of 1 increased significantly upon cooling, while finer structures appeared at 556 nm and 595 nm. At 100 K, the lifetimes of the major emission peaks (τ = 86.5 μs at 556 nm, 83.0 μs at 578 nm, and 86.8 μs at 595 nm) were nearly identical, and significantly longer than those recorded at 300 K. The fine structures could be attributed to a manifestation of the vibronic structure. We propose that this increased emission intensity and the prolonged emission lifetimes at low temperatures can be attributed to the suppression of non-radiative decay via restricted intramolecular motion (RIM) of the less rigid structures including −Ph and −NH− groups, which decelerates its radiative transition to the ground state.

2.3. Selective PL Response of 1 Toward Small Alcohol Molecules

Compound 1 was stable toward UV light (365 nm, 0.5 W, 24 h). The PL response of 1 toward moisture and volatile organic compound (VOC) vapors was investigated. As shown in Figure 5, the emission spectra of 1 in air remained virtually unchanged upon exposure to moisture and VOC vapors including ethyl ether (Et2O), n-hexane, CH2Cl2, CHCl3, acetone, ethyl acetate (EA), petroleum ether (PE), THF, butanol (BuOH), propanol (PrOH), isopropanol (iPrOH), and MeCN. By contrast, the maximum emission wavelength shifted to 615 nm on exposure to EtOH vapor, and then to 645 nm on exposure to saturated MeOH vapor.
The vapor-chromic PL of 1 was more significant in MeOH vapor and so was investigated in detail. The time-dependent emission spectra of 1 on exposure to MeOH vapor is shown in Figure 6a. During the first 5 min, the emission at 539 nm slightly blue-shifted to 534 nm and evidently weakened, while the emission at 576 nm quenched completely. Simultaneously, a low-energy (LE) band was observed at 645 nm. On prolonged exposure, the emission intensity at 534 nm continuously decreased, whereas that at 645 nm increased. After 80 min, the intensities of the two emission peaks were stable. The corresponding CIE chromaticity coordinates (Figure 6b) migrated from yellow (0.45, 0.51) at 0 min to orange (0.54, 0. 38) at 80 min, exhibiting a visible PL color change (Figure 7). A solid sample of 1 saturated with MeOH vapor (1m) exhibited an orange PL with longer lifetime (14.6 μs at 645 nm) and reduced QY (0.70%) compared to that of 1 at room temperature. As shown in Figure 7a, this yellow to orange color change of 1 to 1m was visible to the naked eye. Additionally, when 1m was placed in air for 1 day, its emission color reverted to bright yellow. The recovered solid (1r) emitted at 537 nm and 578 nm (λex = 370 nm, Figure S4), similar to that of 1. This interconversion was repeated over 5 cycles (Figure 7b), indicating the reproducible vapor-chromic PL of 1 towards MeOH vapor.

2.4. Mechanism Study on the PL Response of 1 Toward MeOH

The conversion from 1 to 1m caused the fragmentation of the single crystal, thus the structure of 1m could not be determined by SCXRD. TGA curves of 1m and 1r (Figure S5) showed weight losses of 8.6% (1m, below 110 °C) and 2.3% (1r, below 112 °C), corresponding to the loss of two MeOH molecules (calcd. 8.8%) and one water molecule (calcd. 2.7%), respectively. The IR spectrum of 1m (Figure 8a) showed a strong signal at 1026 cm−1 and broad peaks in the range of 3200–3400 cm−1, attributable to the C–O and –OH stretching vibrations of MeOH, respectively. The signals at 3051, 2947, and 2833 cm−1 were assignable to the C–H stretching vibration of the –Me group. Additionally, the IR spectrum of 1r was similar to that of 1, indicating they possessed a similar solid-state structure. We therefore propose that the conversion from 1 to 1m is due to the substitution of the lattice H2O molecule by two MeOH molecules, while the recovery of 1m to 1r originated from the coordination of H2O molecules when MeOH was eliminated. The powder X-ray diffraction (PXRD) pattern (Figure 8b) of 1 matched well with that simulated from its SCXRD data, whereas that of 1m was completely different, suggesting that the incorporation of MeOH with 1 led to the formation of a new crystalline phase. By contrast, the major peak positions of 1r were closer to that of 1, despite some minor difference in intensity, indicating that the crystalline phase was generally recovered when MeOH was replaced by H2O. There was no void in the crystal structure of 1 (calculated by PLATON v1.18). Therefore, when the H₂O molecules were substituted by larger MeOH molecules, the crystal lattice of 1 is distorted and causes the crystalline phase transformation and shattering. Larger EtOH molecules could only partially replace H2O, exerting a smaller impact on the PL than the MeOH molecules. Other larger and less polar VOC molecules were not able to replace the H2O.
When the solvent H2O molecule was removed from 1 under vacuum at 150 °C for 2 h, the emission spectra of the dehydrated solid (Figure S6) showed a LE band at 690 nm and a weak HE band at 556 nm, which was different from that of 1, suggesting the removal of the H2O molecule induced the changing of the PL. The crystal structure of 1 revealed that a number of intra- and inter-molecular hydrogen bonds joined the H2O molecules with Cl− anions and the −CH2−, −phen, and −NH− groups (Figure 9 and Table S3). In addition, an intermolecular C–H∙∙∙π interaction was observed between the H atoms on the −phen group (C6−H6) and one −Ph ring (C14-C19, Figure 9 and Table S4). These interactions restrict the rotation of the −Ph ring, inhibiting non-radiative decay, and maintaining PL intensity. However, when the H2O molecules were substituted by MeOH, some hydrogen bonds would be disrupted, affecting the electron densities of the −phen group, varying the PL transition energy, with concomitant weakening and eventual disappearing of the HE band of 1, as well as enhancing the LE band of 1m.
The relative binding of MeOH and H2O was investigated by measuring the in situ emission spectra of 1 in mix vapors of MeOH and H2O (generated from the volatilization of mixed solvents with varying volume ratios of MeOH and H2O). As shown in Figure 10, the emission spectrum of 1 exhibited almost no change when the content of MeOH was below 98% (v/v). However, in the case of 98%, the peak at 539 nm slightly blue-shifted to ~534 nm, while the LE band at 645 nm became pronounced. When the volume fraction of MeOH was further increased to 98.5%, 99%, and 100%, the HE band was significantly weakened, accompanied by enhancing of the LE band. These results indicate that the H2O molecules in 1 bind more tightly, and significant PL change could only be triggered when the content of MeOH was higher than 98%.

3. Experimental Section

3.1. Materials and Methods

Dppmaphen was prepared by a literature method [48]. All other materials were obtained from commercial sources and used as received. Elemental (C, H, and N) analyses were measured on a Thermal Fisher Flash Smart microanalyzer (Thermo Fisher Scientific, Waltham, MA, USA). PXRD patterns were acquired on a Bruker D2 Phaser X-ray diffractometer (Bruker, Billerica, MA, USA) with a Cu Kα source (30 kV, 10 mA). Infrared (IR) spectra were obtained on a Bruker VERTEX 70 FT-IR spectrometer (4000−600 cm−1) (Bruker, Billerica, MA, USA) with an ATR probe. NMR spectra were measured at ambient temperature on a Varian UNITY plus-400 spectrometer (Agilent Technologies, Palo Alto, CA, USA), with chemical shifts (δ, ppm) referenced to TMS and the solvent signal of DMSO-d6. Emission spectra, transient photoluminescence, and QY measurements were performed on an Edinburgh FLS1000 spectrometer (Edinburgh Instruments, Livingston, UK). Low temperature PL spectra were measured in an Oxford OptistatDN cryostat (Oxford Instruments, Abingdon, Oxfordshire, UK). Thermogravimetric analysis (TGA) was collected on a TA SDT-2960 analyzer (TA Instruments, New Castle, DE, USA) in a N2 stream with a heating rate of 10 °C/min.

3.2. Synthesis of [Pt(dppmaphen)Cl]Cl·H2O (1)

A DMSO solution (0.5 mL) containing PtCl2 (10.6 mg, 0.04 mmol) was mixed with a MeCN solution (1 mL) containing dppmaphen (15.7 mg, 0.04 mmol), and stirred for 6 h to obtain a yellow turbid solution. The solids were separated by centrifugation, then dissolved in a mixed solution of CH2Cl2 (1.25 mL) and EtOH (0.25 mL), and diffused with n-hexane. Yellow crystals of 1 were isolated after 10 days. Yield: 6.0 mg (22% based on Pt). Anal. calcd. for C25H22Cl2N3OPPt: C, 44.33; H, 3.27; N, 6.20. Found: C, 43.85; H, 3.36; N, 6.10. IR (ATR, cm−1): 3326 (m), 3226 (m), 2983 (w), 2932 (m), 2879 (m), 1632 (s), 1613 (w), 1589 (m), 1563 (s), 1519 (m), 1475 (m), 1440 (m), 1419 (m), 1373 (s), 1293 (m), 1274 (m), 1218 (w), 1157 (m), 1117 (m), 1103 (s), 1079 (m), 999 (m), 954 (m), 917 (m), 884 (m), 845 (vs), 790 (m), 773 (w), 747 (vs), 716 (s), 692 (vs), 657 (m). 1H NMR (400 MHz, DMSO-d6, ppm) δ 9.88 (d, J = 14.5 Hz, 1H), 9.43 (dd, J = 6.5, 2.6 Hz, 1H), 9.05–8.97 (m, 1H), 8.40 (d, J = 9.1 Hz, 1H), 8.20 (dd, J = 7.5, 6.0 Hz, 1H), 8.11–8.03 (m, 2H), 7.99–7.89 (m, 4H), 7.72–7.58 (m, 6H), 7.41 (d, J = 9.1 Hz, 1H), 4.74 (s, 2H). 13C NMR (101 MHz, DMSO-d6, ppm) δ 156.51, 147.81, 146.76, 143.67, 141.89, 138.70, 134.08, 132.97, 133.00, 130.66, 129.61, 129.50, 128.42, 125.13, 124.69, 124.04, 120.38. 31P {1H} NMR (162 MHz, DMSO-d6, ppm) δ -1.07.

3.3. PL Response of 1 Toward VOC Vapors and Moisture

Solid samples of 1 were coated on quartz slides and then sealed in a quartz cell with a small tube containing 0.1 mL VOC or water. The emission spectra were recorded after 10 min.

3.4. Detection of MeOH in Aqueous Solutions

Solid samples of 1 were coated on quartz slides and sealed in a quartz cell with a test tube containing a MeOH/H2O mixture (0.1 mL) of different ratios (v/v). The emission spectra were measured in situ after 10 min.

3.5. Crystallography

A suitable crystal of 1 was selected directly from the recrystallization solvent. The diffraction data were collected on a Bruker APEX II diffractometer (Bruker, Billerica, MA, USA) with Mo Kα radiation (0.71073 Å) at 223 K. The data were reduced by Bruker SAINT (Bruker, Billerica, MA, USA), and adsorption (mult-iscan) correction was applied using SADABS-2016/2. The structures were solved by direct methods and refined by full-matrix least-squares methods against F2 using the SHELXT (Sheldrick, 2018) program package [49]. All nonhydrogen atoms were refined anisotropically. The H atoms of the water molecular were located from the Fourier map and then constrained to ride over the O1 atom. All other hydrogen atoms were placed at calculated positions and refined using a riding model. Selected crystallographic data and refinement parameters are listed in Table S1. Selected bond lengths and angles are listed in Table S2.

3.6. TD-DFT Computational Details

Theoretical calculations over the frontier orbital distribution were conducted using the Gaussian 16-C01 software package [50] at the B3LYP-GD3BJ/def2SVP level.

4. Conclusions

In summary, a new Pt(II) complex [Pt(dppmaphen)Cl]Cl·H2O (1) was synthesized by the reaction of dppmaphen with PtCl2. Upon excitation at 370 nm, solid-state 1 exhibits yellow phosphorescence with emission bands centered at 539 and 576 nm. The emission of 1 shifted to 645 nm upon exposure to MeOH vapor, accompanied by a visible PL color change from yellow to orange. The original PL recovered in air over one day. This chromic PL response was selective for MeOH and, to a lesser extent, EtOH. We propose that this selective response arises from the reversible substitution of H2O molecules by MeOH, which induces a lattice distortion of 1, resulting in the disruption and reorganization of the original noncovalent interactions (hydrogen bonding and C−H∙∙∙π interactions) in 1, thereby affecting the electron densities of the −phen group, varying the PL transition energy, and causing this visible PL color change.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/inorganics13050170/s1, Figure S1: IR spectrum of 1; Figure S2: NMR spectra of 1; Figure S3: TGA curve of 1; Figure S4: The emission spectra of 1r; Figure S5: TGA curves of 1m and 1r; Figure S6: The emission spectra of dehydrated 1; Table S1: Selected crystallographic data and refinement parameter for 1; Tables S2–S4: Lengths and angles for selected bonds, hydrogen bonds, and C−H···π interactions in 1.

Author Contributions

Conceptualization, Z.-G.R. and H.-X.L.; methodology, Y.H.; software, Y.H. and Y.L.; validation, Y.H. and J.W.; formal analysis, Y.H. and J.W.; investigation, Y.H.; resources, Z.-G.R.; data curation, Y.H.; writing—original draft preparation, Y.H.; writing—review and editing, Z.-G.R., Y.L. and D.J.Y.; supervision, Z.-G.R. and H.-X.L.; project administration, Z.-G.R.; funding acquisition, Z.-G.R. All authors have read and agreed to the published version of the manuscript.

Funding

This research was financially supported by the National Natural Science Foundation of China (Grant No. 21671144).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The crystallographic data are available from the Cambridge Crystallographic Data Centre (CCDC number 2445242). Other data not presented in the Supplementary Materials are available on request from the corresponding author.

Conflicts of Interest

The authors declare no conflicts of interest.

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Inorganics 13 00170 sch001
Scheme 1. Synthesis of [Pt(dppmaphen)Cl]Cl∙H2O (1).
Scheme 1. Synthesis of [Pt(dppmaphen)Cl]Cl∙H2O (1).
Inorganics 13 00170 sch001
Inorganics 13 00170 g001
Figure 1. Crystal structure of 1 at 30% thermal ellipsoids. All hydrogen atoms are omitted for clarity.
Figure 1. Crystal structure of 1 at 30% thermal ellipsoids. All hydrogen atoms are omitted for clarity.
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Figure 2. (a) Excitation (dashed and dotted curves) and emission (solid curve) spectra of solid-state 1 at room temperature. (b) Photographs of solid-state 1 under natural light and under UV light (365 nm, 0.5 W).
Figure 2. (a) Excitation (dashed and dotted curves) and emission (solid curve) spectra of solid-state 1 at room temperature. (b) Photographs of solid-state 1 under natural light and under UV light (365 nm, 0.5 W).
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Figure 3. Distributions of the frontier orbitals of compound 1 (isovalue = 0.03).
Figure 3. Distributions of the frontier orbitals of compound 1 (isovalue = 0.03).
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Figure 4. Emission spectra of solid-state 1 (λex = 370 nm) between 100–300 K with 20 K interval.
Figure 4. Emission spectra of solid-state 1 (λex = 370 nm) between 100–300 K with 20 K interval.
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Figure 5. Emission spectra of solid-state 1 (λex = 370 nm) in a cell filled with the vapors of common solvents.
Figure 5. Emission spectra of solid-state 1 (λex = 370 nm) in a cell filled with the vapors of common solvents.
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Figure 6. (a) Time-dependent emission spectra of 1 on exposure to MeOH vapor over 80 min at 4 min intervals and (b) the corresponding CIE color space chromaticity diagram (λex = 370 nm).
Figure 6. (a) Time-dependent emission spectra of 1 on exposure to MeOH vapor over 80 min at 4 min intervals and (b) the corresponding CIE color space chromaticity diagram (λex = 370 nm).
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Figure 7. (a) Photographs of 1, 1m and 1r under UV light (365 nm, 0.5 W). (b) Maximum emission wavelengths of 1 over the 5-round MeOH vapor/Air exposure cycles.
Figure 7. (a) Photographs of 1, 1m and 1r under UV light (365 nm, 0.5 W). (b) Maximum emission wavelengths of 1 over the 5-round MeOH vapor/Air exposure cycles.
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Figure 8. Comparisons of (a) the IR spectra and (b) the PXRD patterns of 1, 1m and 1r.
Figure 8. Comparisons of (a) the IR spectra and (b) the PXRD patterns of 1, 1m and 1r.
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Figure 9. Hydrogen bonds (green dashed lines) and C−H∙∙∙π interactions (blue dashed lines) in 1.
Figure 9. Hydrogen bonds (green dashed lines) and C−H∙∙∙π interactions (blue dashed lines) in 1.
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Figure 10. Emission spectra of 1 in vapors generated by different concentrations of MeOH/H2O (v/v, λex =370 nm).
Figure 10. Emission spectra of 1 in vapors generated by different concentrations of MeOH/H2O (v/v, λex =370 nm).
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MDPI and ACS Style

Hu, Y.; Wang, J.; Young, D.J.; Li, H.-X.; Lu, Y.; Ren, Z.-G. A Pt(II) Complex with a PNN Type Ligand Dppmaphen Exhibits Selective, Reversible Vapor-Chromic Photoluminescence. Inorganics 2025, 13, 170. https://doi.org/10.3390/inorganics13050170

AMA Style

Hu Y, Wang J, Young DJ, Li H-X, Lu Y, Ren Z-G. A Pt(II) Complex with a PNN Type Ligand Dppmaphen Exhibits Selective, Reversible Vapor-Chromic Photoluminescence. Inorganics. 2025; 13(5):170. https://doi.org/10.3390/inorganics13050170

Chicago/Turabian Style

Hu, Yuanyuan, Jiangyue Wang, David James Young, Hong-Xi Li, Yuxin Lu, and Zhi-Gang Ren. 2025. "A Pt(II) Complex with a PNN Type Ligand Dppmaphen Exhibits Selective, Reversible Vapor-Chromic Photoluminescence" Inorganics 13, no. 5: 170. https://doi.org/10.3390/inorganics13050170

APA Style

Hu, Y., Wang, J., Young, D. J., Li, H.-X., Lu, Y., & Ren, Z.-G. (2025). A Pt(II) Complex with a PNN Type Ligand Dppmaphen Exhibits Selective, Reversible Vapor-Chromic Photoluminescence. Inorganics, 13(5), 170. https://doi.org/10.3390/inorganics13050170

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