Chemical Sciences - Adaptive Sensor Group

Chemical Sciences - Adaptive Sensors Group

chemical sciences - adaptive sensors group

project page

Name:

Dr. Nameer Alhashimy, B.SC., Ph.D., MRSC.

Contact details

School of Chemical Sciences

Aduptive Information Cluster

National Centre for Sensor Research

Dublin City University

Ireland

Tel: +353-(0)1-7007601

Fax: +353-(0)1-7008021

nameer.alhashimy@dcu.ie

Qualifications

  • Ph.D., in organic chemistry, Dublin City University, Ireland, 2004.
  • B.Sc., in chemistry, Basrah University, Iraq, 1992.

Project Summary

Ion receptors (cation, anion) are one of the hottest area in the organic and inorganic chemistry due to its importance in the presence of wide-ranging fields, from biology, medicine and in the environment. Our research is involved in the design, synthesis, purification and characterization of different types of ion receptors particularly optical sensors and macrocyclic chemoreceptors.

Optical sensors:

  • Photochromism and switchable spiropyran compound

Photochromic compounds show the ability to changing colour upon external radiation with different wavelengths leading to ever increasing application. One of the significant classes of photochromic organic compounds at present are spiropyrans, which have photoswitches poperties, forming the equilibrium state of quinoidal-zwitterionic structures, highly colored, under UV light and rearrange reversibly to the spiro form, color less, under VIS light, Scheme 1, also see [Aleksander Radu web]. This characteristic features of spiropyran will allow the availability of a binding sight in the open form presenting by phenolate moiety which are able to interact with different external guest substrates.

Scheme 1. Equilibrium photoisomerization under external radiation of spiropyran compound.

The key question in this project is why we are interested in investigating with such compound of tremendous properties?

The answer is basically that spiropyran modified surface have many potential applications:

  • Variety of detection modes; fluorescence, EC, UV-Vis, raman...
  • Tuning of host-guest activity through modification of local surface polarity.
  • Modification of binding site activity.
  • Modulated surface interaction with charged species-separations.
  • Controlled surface charged and wettability.
  • Modulated surface solution conductivity.

My part in this project is the modification of an already synthesised spiropyran derivative SP-1 Figure 1. This compound exhibits the capability of reversible metal ion binding with CO+2 ion [1] by using UV and green LED. Compound SP-1 was tethered into polymer covalently through diamine spacer Scheme 2. Also it showed similar photonically controlled behaviour with certain amino acids due to the formation of complementary zwitterionic complexes [1]. Also there was additional investigation in terms of controlling the spiropyran-merocyanine system on modified surfaces, [1].

Figure 1. Photoswitchable derivative of spiropyran compound.

We have also synthesised new spiropyran derivatives with different substituent groups in different positions at pyran group that are expected to bind different ions/metals and also demonstrate comparison between derivatives.

Currently we are attempting to synthesis different derivatives as mono, di and tri spiropyran that can be immobilised into polymer which we expect to exhibit extra strength and selective binding for metals. Also we are looking to utilize this molecular system to have a chance in applications such as drug delivery, chromatographic separation and conducting polymers.

  • Calix[4]arene attached with urea and pyrene excimer functionality

We have been sharing in the design, synthesis, pre-purification and characterization of new optical sensor 1 for Cl- anion selective [2], Figure 2.

This compound is the first synthesis which consists of calixarene as scaffold which is in a 1,3-alternate configuration, bearing symmetrically on both upper and lower rim di-urea, methylene spacer and two pyrene moieties. This tweezer shaped compound allows the selective chloride detection through hydrogen bonding of urea amongst various anion tested [Ben Schazmann web].

Figure 2. Calix[4]arene optical sensor based on urea and excimer pyrene moieties showed a good selectivity for Cl- anion.

Macrocyclic chemo-receptors:

  • Homochiral tripodal receptors

We were also involved in the synthesis and full characterization including crystallographic studies, of new homochiral tripodal receptors as efficient compounds to bind different anions [3] and discriminate between two different enantiomers [5] Figure 3.

Figure 3. Homochiral tripodal receptors exhibit selectivity for different anions.

Crystallographic studies were also demonstrated of compound 1(a,b), which is the first report of an x-ray structure for the tripodal imidazolium receptor containing a 1,3,5-trimethylphenyl spacer Figure 4.

Figure 4. Side views of the crystal structures of (1a) (up) and 1(b) (down) (hydrogens are not shown for clarity).

Publications

Articles:

  1. Benjamin Schazmann, Nameer Alhashimy, and Dermot Diamond, J. Am. Chem. Soc., 2006, 128, 8807-88014. (A Chloride Selective Calix[4]arene Optical Sensor Combining Urea Functionality With Pyrene Excimer Transduction).
  2. Nameer Alhashimy, Dermot J. Brougham, Joshua Howarth, Alan Farrell, Brid Quilty and Kieran Nolan. Tetrahedron letters, In press. (Homochiral tripodal imidazolium receptors: structural and anion-receptor studies)
  3. Shane O’Mally, Nameer Alhahsimy, Kieran Nolan, John Mahony, Aislling Kieran, Mary Pryce, Tetrahedron Letters, In press. (The Selective Preparation of Partial Cone O-Aryl Ether from 1,3-Dimethoxycalix[4]arene: A New Platform for the Non-Aggregated Dyes).
  4. Nameer Alhashimy, Joshua Howarth, Tetrahedron Letters, 2001, 42, 5777-5779. (A homochiral tripodal receptor with selectivity for sodium(S)-2-aminopropoinate over sodium(R)-2-aminopropoinate).
  5. Nameer Alhashimy, Kieran Nolan, Organic Chemistry letters, accepted. (The synthesis and crystallographic characterization of a homochiral imidazoleylidene-Pd(II) complex).

Posters:

  • Robert Byrne, Aleksander Radu, Nameer Alashimy, Conor Slater, William S. Yerazunis and Dermot Diamond, Poster presentaion, European coatings conference, 15/16 May, Berlin, Germany . (Photoswitchable Surfaces For Sensing Applications).
  • Aleksandar Radu, Robert Byrne, Nameer Alhahsimy, Dermot Diamond. Abstracts of Papers, 231st ACS National Meeting, Atlanta, GA, United States, March 26-30, 2006. (Spiropyran-based smart surfaces: Development and characterization).
  • Nameer Alhashimy, Kieran Nolan, Dermot J. Brougham, Poster presentation at Lisbon/ Portugal (15/10/2003): International conference on the synthetic Receptors. (The synthesis and application of novel homochiral tripodal anion receptors).

Presentation:

· Oral presentation at school of chemical sciences, DCU, Ireland, February 2003, to academics and 4th year students. (The synthesis and application of novel homochiral tripodal azolium salts).

Further Information