Authors Research group(s) Collaborations

Thematic Strand Advanced Materials

Funding

Thematic Strand Environment & Cultural Heritage

Lanthanide based Materials in Spintronics, Environmental

and Sensor Applications

First example of an observable and reversible case of thermochromism due to the interaction of an alkylphosphonium [P6,6,6,14] + with a

β-diketonate of the room temperature ionic liquid (RTIL) [P6,6,6,14][Eu(fod)4] (1).

Single Molecule Magnets (SMMs) have several potential applications but the blocking temperatures (TB) of SMMs need to be considerably improved. As so, fundamental knowledge in understanding the principles behind SMMs is still required in order to obtain increases in TB values, hopefully to liquid nitrogen temperatures and beyond. In an ongoing work we describe an experimental and theoretical study of the magnetic properties of LLHs materials (Ln8(OH)20Cl4•6H2O, Ln = Dy, Tb, Ho, Er), both diluted in the diamagnetic Y analogous matrix and intercalated with a large anion (2,6-naphtalene dicarboxylate).

• Societal challenge “Climate action, environment, resource efficiency and raw materials” • Societal challenge “Food security, sustainable agriculture and forestry, marine and maritime and inland water research, (…)”

• Societal challenge “Food security, (…)”

• Societal challenge “Secure, clean and efficient energy” • Societal challenge “Climate action, environment, resource efficiency and raw materials”

• Molecular magnetism, molecular spintronics, quantum computing

Backcover Picture: Chem. Commun., 2017, 53, 850-853.

By changing the ligands of the Eu(II) complex with dibenzoylmethanate (dbm) we prepared the RTIL [P6,6,6,14][Eu(fod)3(dbm)] (2), while calorimetric measurements showed a melting point at 415 K for [P6,6,6,14][Eu(dbm)4] (3). The luminescence quantum yields determined for 1, 2, and 3 are, 34%, 59 %, and 64 % respectively, with the highest values being comparable with the maximum values reported for complexes of the same type

Alcohol Optical Sensor

Structure of [P6,6,6,14][Eu(fod)4] formed at 80 ºC. Pictures were taken under daylight (left) and

under 366 nm UV irradiation (right).

Using only the organic moieties from compound 1 we prepared the RTIL [P6,6,6,14][fod].

Heating the ionic liquid [P6,6,6,14][fod] at 80 ºC the solvatochromic keto-phosphorane like compound P6,6,6,14fod is formed.

Non alcohols: Acetonitrile

Dichloromethane

Alcohols: Methanol Ethanol

Sensor mechanism: The reddish P6,6,6,14fod when solvated by alcohol molecules turns yellow, returning to reddish upon driyng.

Keywords Layered Lanthanide Hydroxides

Single Molecule Magnets Phosphorus Remediation

Optical Sensors Nanomaterials

Problems addressed: the urgency, of building efficient and low cost anion sensors/scavengers for phosphate, arises from the heavy use of phosphate as a where 70−80% of applied phosphorus is lost and accumulates in nature. Also, phosphorus is one of the major nutrients contributing to eutrophication of rivers and lakes. Production of phosphate rock is predicted to reach its peak possibly as early as the next few decades, despite its growing demand. Industrially recovered phosphate needs to be purified in a costly process with treatments not suitable for rural areas where the building costs and maintenance of wastewater treatment plants would be too high. The only validated method for measuring soluble phosphate in water is a colourimetric technique from the 1960s difficult to adapt for on-line measurements. Phosphate anion’s lack of electrochemical activity, together with its high hydration energy, make direct detection and transduction challenging.

LEuH material intercalated with 2,6-naphtalene dicarboxilate, LEuH-2,6-NDC, acts as a dual-channel sensor towards anions. The sensor was tested with several biological relevant anions showing high selectivity towards phosphate

LEuH, Eu8(OH)20Cl4•6H2O, presents high phosphate sequestration capacity followed by controlled release of phosphate with improved adsorbant stability.

Adsorption procedure

100 mL water-batch experiments pH ≈ 7 < 200 rpm shaking , 24 h 0.030 g of LEuH ([LEuH] = 300 mgL-1) 0.01735 g of Na2HPO4•12H2O ([P] = 15 mgL

-1)

24 mg of P/ 1 g of LEuH

Desorption procedure

100 mL water-batch experiments < 200 rpm shaking , 24 h [NaOH] = 1 M [NaCl] = 1 M

60 % desorption

ILs were immobilized into 3D MOFs, and these composites were incorporated in a polymer matrix to yield [IL@MOF]@Matrimid®5218. This method proved to be an efficient strategy to improve the permeability and selectivity toward mixtures of CO2/N2, presenting also a remarkable improvement in membrane flexibility and mechanical resistance.

IL@MOF

[EMIM][CN3]

Ionic Liquids

[TMG][N3]

This is one of the very few studies reporting dramatic enhancement of IL@MOF in respect to CO2/N2 separation. Although the Robeson´s upper bound was not surpassed, we confirmed that this method is an excellent approach to surpass this limit even with a very low upload of IL@MOF composite. This work clearly shows that the careful design and selection of the structures of IL and MOFs is crucial to obtain a membrane with simultaneously high permeability and high selectivity.

LLH unit cell viewed down the (a) c axis, (b) b axis, and (c) a axis.

Theor. calc. by the REC model:

Dy1 Dy2 Dy3 ground dublet

0.76 |±13/2> 0.98 |±15/2> 0.99 |±15/2>

gz 16.2 19.79 19.91

2 coordination geometries [Dy(OH)7(H2O)] dodecahedron polyhedron

[Dy(OH)8(H2O) ] monocapped square antiprism

The experimental results, supported by theoretical calculations, put separately into evidence and explained the single ion, 2D and 3D Ln-Ln interaction effects. This was the first time that such a clear separation and detailed analysis has been achieved in a layered lanthanide compound, and LDyH was the first example of SMM behavior in a layered rare earth compound and the first Ln SMM with more than 12 metal ions.

Claudia C.L. Pereira4,1, César A.T. Laia4, João C. Lima4, Artur J. Moro4, Jose ́ J. Baldoví5, Eugenio Coronado5, Alejandro Gaita- Ariño5

PSCG | Photochemistry and Supramolecular Chemistry Group, Department of Chemistry, Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, Portugal MMRT | Molecular Materials Research Team, Instituto de Ciencia Molecular, Universitat de València, Spain.

1 RS | Radiopharmaceutical Sciences Group 2 RPS | Radiation Protection and Safety Group 3 REI | Radiation, Elements and Isotopes Group 4 NET | Nuclear Engineering and Techniques Group 5 QEf | f-element Chemistry Group 6 SS | Solid State Group

C2TN members: Bernardo Monteiro5,*, Joaquim Marçalo5, João P. Leal,5 Joana T. Coutinho 6, Laura C.J. Pereira6, Manuel Almeida6, Maria H. Casimiro3, Luis M. Ferreira3

http://c2tn.tecnico.ulisboa.pt RADIATION FOR SCIENCE AND SOCIETY C

2TN/IST acknowledges Fundação para a Ciência e a Tecnologia for

financial support under the project UID/Multi/04349/2013