Skip to content
Research Article Open access CC BY 4.0

Luminescence of the Conjugate Bases of [2-(2-Hydroxyphenyl)phenyl]phosphinic Acid and Single-Crystal X-Ray Structure Determination of Sodium [2-(2-Hydroxyphenyl)phenyl]phosphinate

Valeria Gagliardi, Jesús Castro, Valentina Beghetto, María Expósito, Marco Bortoluzzi

Organics · pp. 10–10 · Published 3 Mar 2025

10.3390/org6010010

Abstract

The commercial flame-retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) was almost quantitatively converted in sodium [2-(2-hydroxyphenyl)phenyl]phosphinate Na[OH-Ph-Ph-PHO2] and disodium 2-(2-phosphinatophenyl)benzen-1-olate Na2[O-Ph-Ph-PHO2] under mild reaction conditions and without the use of toxic reactants. The structure of Na[OH-Ph-Ph-PHO2] was determined by means of single-crystal X-ray diffraction. The inter- and intramolecular Na-O interactions generate a stair-like framework where the sodium cations are five-coordinated and exhibit a highly distorted coordination sphere. The two compounds are characterized by appreciable blue luminescence at the solid state upon excitation with UV light, attributed to S1→S0 decays on the basis of time-resolved measurements and computational calculations. The photoluminescence quantum yield is higher for Na2[O-Ph-Ph-PHO2], and the emission and excitation bands are shifted at longer wavelengths. The disodium salt showed affinity towards cellulose, and doped Na2[O-Ph-Ph-PHO2]@cellulose samples maintained emission features comparable to those of the pure compound. The nature of the interaction between cellulose and the emitting species was studied by means of periodic density functional theory calculations, that highlighted the role of the sodium cations.

Phosphinate Chemistry Conjugate X-ray Single crystal Sodium Crystal structure Luminescence

References (78)

  1. 1 Saito, T. (1972). Cyclic Organophosphorus Compounds and Process for Making Same. (US3702878A).
  2. 2 Visakh, P.M., and Arao, Y. (2015). A Review of Non-halogen Flame Retardants in Epoxy-Based Composites and Nanocomposites: Flame Retardancy and Rheological Properties. Flame Retardants, Springer. [DOI]
  3. 3 Rakotomalala, 2010, Recent Developments in Halogen Free Flame Retardants for Epoxy Resins for Electrical and Electronic Applications [DOI]
  4. 4 Waaijers, 2013, Toxicity of new generation flame retardants to Daphnia magna [DOI]
  5. 5 Hirsch, 2017, Multiparameter toxicity assessment of novel DOPO-derived organophosphorus flame retardants [DOI]
  6. 6 White, K.M., Angell, Y.L., Angell, S.E., and Mack, A.G. (2010). Dopo-Derived Flame Retardant and Epoxy Resin Composition. (WO2010135393A1).
  7. 7 Kishimoto, D., and Umeki, Y. (2016). High Melting Point Flame Retardant Crystal and Method for Manufacturing the Same, Epoxy Resin Composition Containing the Flame Retardant, and Prepreg and Flame Retardant Laminate Using the Composition. (US20130053473A1).
  8. 8 Dittrich, U., Just, B., Döring, M., and Ciesielski, M. (2008). Process for the Preparation of 9,10-dihydro-9-oxa-10-organylphosphaphenanthrene-10-oxide and Derivatives of the Same Substituted on the Phenyl Groups. (US20050038279A1).
  9. 9 Stelzig, T., Bommer, L., Gaan, S., and Buczko, A. (2018). DOPO-Based Hybrid Flame Retardants. (US20170081590A1).
  10. 10 Gaan, S., Neisius, M., Mercoli, P., Liang, S., Mispreuve, H., and Näscher, R. (2013). Novel Phosphonamidates-Synthesis and Flame Retardant Application. (WO2013020696A2).
  11. 11 Stawinski, 2002, How to Get the Most Out of Two Phosphorus Chemistries. Studies on H-Phosphonates [DOI]
  12. 12 Montchamp, 2014, Phosphinate Chemistry in the 21st Century: A Viable Alternative to the Use of Phosphorus Trichloride in Organophosphorus Synthesis [DOI]
  13. 13 Salmeia, 2015, An overview of some recent advances in DOPO-derivatives: Chemistry and flame retardant applications [DOI]
  14. 14 Artner, 2008, A Novel DOPO-Based Diamine as Hardener and Flame Retardant for Epoxy Resin Systems [DOI]
  15. 15 Umapathy, 2011, Development and characterization of novel DOPO based phosphorus tetraglycidyl epoxy nanocomposites for aerospace applications [DOI]
  16. 16 Lin, 2014, Synthesis of a Phosphinated Acetoxybenzoic Acid and Its Application in Enhancing Tg and Flame Retardancy of Poly(ethylene terephthalate) [DOI]
  17. 17 Lin, 2016, Synthesis of a novel highly effective flame retardant containing multivalent phosphorus and its application in unsaturated polyester resins [DOI]
  18. 18 Wang, 2019, Synthesis of a novel flame retardant based on DOPO derivatives and its application in waterborne polyurethane [DOI]
  19. 19 Chen, 2021, DOPO-based curing flame retardant of epoxy composite material for char formation and intumescent flame retardance [DOI]
  20. 20 Wang, 1998, Synthesis and properties of epoxy resins containing 2-(6-oxid-6H-dibenz<c,e><1,2>oxaphosphorin-6-yl)1,4-benzenediol [DOI]
  21. 21 Bai, 2013, Preparation, flame retardancy, and thermal degradation of unsaturated polyester resin modified with a novel phosphorus containing acrylate [DOI]
  22. 22 Liu, 2013, Preparation, characterization and properties of a halogen-free phosphorous flame-retarded poly(butylene terephthalate) composite based on a DOPO derivative [DOI]
  23. 23 Zhang, 2013, Synthesis and properties of a modified unsaturated polyester resin with phosphorus-containing pendant groups [DOI]
  24. 24 Artner, 2007, A Novel and Effective Synthetic Approach to 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) Derivatives [DOI]
  25. 25 Koenig, 2012, Flame retardancy working mechanism of methyl-DOPO and MPPP in flexible polyurethane foam [DOI]
  26. 26 Wagner, 2012, Synthesis of new organophosphorus compounds using the Atherton–Todd reaction as a versatile tool [DOI]
  27. 27 Buczko, 2014, Bridged DOPO derivatives as flame retardants for PA6 [DOI]
  28. 28 Berchel, 2014, Atherton–Todd reaction: Mechanism, scope and applications [DOI]
  29. 29 Jian, 2016, Synthesis of a Novel P/N/S-Containing Flame Retardant and Its Application in Epoxy Resin: Thermal Property, Flame Retardance, and Pyrolysis Behavior [DOI]
  30. 30 Zhang, 2017, Highly Effective P–P Synergy of a Novel DOPO-Based Flame Retardant for Epoxy Resin [DOI]
  31. 31 Neisius, 2014, Synthesis of DOPO-Based Phosphonamidates and their Thermal Properties [DOI]
  32. 32 Vasiljević, J., Čolović, M., Čelan Korošin, N., Šobak, M., Štirn, Ž., and Jerman, I. (2020). Effect of Different Flame-Retardant Bridged DOPO Derivatives on Properties of in Situ Produced Fiber-Forming Polyamide 6. Polymers, 12. [DOI]
  33. 33 Salmeia, 2018, Industrial Upscaling of DOPO-Based Phosphonamidates and Phosphonates Derivatives Using Cl2 Gas as a Chlorinating Agent [DOI]
  34. 34 Salmeia, K.A., Flaig, F., Rentsch, D., and Gaan, S. (2018). One-Pot Synthesis of P(O)-N Containing Compounds Using N-Chlorosuccinimide and Their Influence in Thermal Decomposition of PU Foams. Polymers, 10. [DOI]
  35. 35 Salmeia, 2018, Comprehensive study on flame retardant polyesters from phosphorus additives [DOI]
  36. 36 Li, 2019, Electrochemical Dehydrogenative Coupling of Alcohols with Hydrogen Phosphoryl Compounds: A Green Protocol for P−O Bond Formation [DOI]
  37. 37 Xiong, 2018, DCC-assisted direct esterification of phosphinic and phosphoric acids with O-nucleophiles [DOI]
  38. 38 Lee, 2014, Syntheses and flame retarding properties of DOPO polymers, melamine polymers, and DOPO-melamine copolymers [DOI]
  39. 39 Agostinis, L., Ghincolov, S., and Bortoluzzi, M. (2023). Preparation Process of P(=O)-Heteroatom Derivatives of Dibenzooxaphosphacycles. (WO2023094526A1).
  40. 40 Bortoluzzi, 2023, Straightforward synthesis of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide derivatives containing P–N bonds [DOI]
  41. 41 Marra, G., Bortoluzzi, M., and Agostinis, L. (2023). One-Pot Synthesis of Phosphoramidates from dibenzo[1,3,2]dioxaphosphepine-6-oxide. Chem. Proc., 14. [DOI]
  42. 42 Bortoluzzi, M., Ghincolov, S., and Agostinis, L. (2023). Alternative Synthesis of Phosphonate Derivatives of 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. Chem. Proc., 14. [DOI]
  43. 43 Ferraro, 2023, Dual-emitting Mn(II) and Zn(II) halide complexes with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide as ligand [DOI]
  44. 44 Lai, H., Tan, X., Liu, X., Xiong, P., and LI, X. (2018). Method for Synthesizing 9, 10-dihydro-9-oxygen-10-phosphaphenanthrene-10-oxide. (CN105949242A).
  45. 45 Yao, Z., Wang, F., and Cheng, K. (2020). DOPO and Its Intermediate Preparation Method. (CN107556343A).
  46. 46 Zhang, C., Wu, Y., Li, F., Wang, Y., and Wang, J. (2024). Preparation Method of 9, 10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. (CN118373852A).
  47. 47 Doering, M., Lindner, B., and Kaplan, A. (2011). Method for the Production of Dibenz[c,e][1,2]-oxaphosphorin Derivatives, Amino-dibenz[c,e][1,2]-oxaphosphorin and also Use Thereof. (US2010069657A1).
  48. 48 Buysch, H.-J., Glock, V., Griehsel, B., and Komoschinski, J. (1997). Process for Preparing 6-oxo-(6H)-dibenz-[c,e][1,2]-oxaphosphorins (ODOPs). (US5650530A).
  49. 49 Yamada, 1990, A Novel synthesis of 6-hydroxyalkyl- and 6-hydroxy-aralkyl-6H-dibenz[c,e][1,2]oxaphosphorin 6-Oxides [DOI]
  50. 50 Hauck, S., and Leuschner, E.M. (2021). Metal Complexes, Manufacturing Method Thereof, Flame-Retardant Polymer Composition Comprising the Same and Their Use. (WO2021048154A1).
  51. 51 Goedderz, 2020, Coordination Compounds of 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-Oxide (DOPO) Ligands: Extremely High Thermostability and Ligand Oxidation in the Solid State [DOI]
  52. 52 Borys, 2023, An Illustrated Guide to Schlenk Line Techniques [DOI]
  53. 53 Elgrishi, 2018, A Practical Beginner’s Guide to Cyclic Voltammetry [DOI]
  54. 54 Bruker AXS Inc. (2022). APEX4 v.2022.1-1, SAINT v.8.40B, XPREP v.2014/2, SADABS-2016/2, Bruker AXS Inc.
  55. 55 McArdle, 2017, Oscail, a program package for small-molecule single-crystal crystallography with crystal morphology prediction and molecular modelling [DOI]
  56. 56 Sheldrick, 2015, SHELXT—Integrated space-group and crystal-structure determination
  57. 57 Sheldrick, 2015, Crystal structure refinement with SHELXL
  58. 58 Spek, 2020, checkCIF validation ALERTS: What they mean and how to respond
  59. 59 Melhuish, 1961, Quantum efficiencies of fluorescence of organic substances: Effect of solvent and concentration of the fluorescent solute [DOI]
  60. 60 Staroverov, 2003, Comparative assessment of a new nonempirical density functional: Molecules and hydrogen-bonded complexes [DOI]
  61. 61 Weigend, 2005, Balanced basis sets of split valence, triple zeta valence and quadruple zeta valence quality for H to Rn: Design and assessment of accuracy [DOI]
  62. 62 Cossi, 2003, Energies, structures, and electronic properties of molecules in solution with the C-PCM solvation model [DOI]
  63. 63 Cramer, C.J. (2004). Essentials of Computational Chemistry, Wiley. [2nd ed.].
  64. 64 Farias, 2019, Predicting Phosphorescence Rates of Light Organic Molecules Using Time-Dependent Density Functional Theory and the Path Integral Approach to Dynamics [DOI]
  65. 65 Neese, 2012, The ORCA program system [DOI]
  66. 66 Neese, 2022, Software update: The ORCA program system-Version 5.0 [DOI]
  67. 67 Perdew, 2008, Restoring the Density-Gradient Expansion for Exchange in Solids and Surfaces [DOI]
  68. 68 Milman, 2000, Electronic structure, properties, and phase stability of inorganic crystals: A pseudopotential plane-wave study [DOI]
  69. 69 Tkatchenko, 2009, Accurate Molecular Van Der Waals Interactions from Ground-State Electron Density and Free-Atom Reference Data [DOI]
  70. 70 Nishiyama, 2002, Crystal Structure and Hydrogen-Bonding System in Cellulose Iβ from Synchrotron X-ray and Neutron Fiber Diffraction [DOI]
  71. 71 Clark, 2005, First principles methods using CASTEP
  72. 72 Rutter, 2018, C2x: A tool for visualisation and input preparation for Castep and other electronic structure codes [DOI]
  73. 73 Álvarez, S., and Llunell, M. (2000). Continuous symmetry measures of penta-coordinate molecules: Berry and non-Berry distortions of the trigonal bipyramid. J. Chem. Soc. Dalton Trans., 3288–3303. [DOI]
  74. 74 Alemany, 2005, Shape maps and polyhedral interconversion paths in transition metal chemistry [DOI]
  75. 75 Addison, A.W., Rao, T.N., Reedijk, J., van Rijn, J., and Verschoor, G.C. (1984). Synthesis, structure, and spectroscopic properties of copper(II) compounds containing nitrogen–sulphur donor ligands; the crystal and molecular structure of aqua[1,7-bis(N-methylbenzimidazol-2′-yl)-2,6-dithiaheptane]copper(II) perchlorate. J. Chem. Soc. Dalton Trans., 1349–1356. [DOI]
  76. 76 Blackman, 2020, Five-coordinate transition metal complexes and the value of τ5: Observations and caveats [DOI]
  77. 77 Shi, 2012, Review: Use of optical brightening agents (OBAs) in the production of paper containing high-yield pulps [DOI]
  78. 78 Roberts, J.C. (1996). Dyes and fluorescent whitening agents for paper. Paper Chemistry, Springer. [DOI]

Cited by 3

3 citations reported by external sources — individual citing-article records aren't available to list yet.

Article metrics

Real usage data collected on this platform.

0

Page views

0

PDF downloads

0

Outbound clicks

3

Citations

Views by country

Approximate, from request IP at view time — not citizenship or institution. Countries with fewer than 5 views are grouped as "Other".

No views recorded yet.

Traffic sources

Referring site, by host.

No traffic recorded yet.

Views and downloads exclude known bots/crawlers. Citations combines this platform's own DOI-resolved index with each external source's own reported total — see Cited by above for individually listed citing works. Last refreshed 0 seconds ago.