CrystEngComm Blog

A recent paper in CrystEngComm details a new synthetic method to create magnenite (iron oxide) nanoparticles (NPs), based on the orientated aggregation of particles using a calixarene macrocycle. The new method allows for control of the type of NPs produced and could potentially be applied to the growth of other nanomaterials.

Magnetite has promising biomedical applications due to its interesting magnetic and electrochemical properties and has been studied for drug delivery, biosensing and cancer treatment.  The NPs can reduce oxidative stress from electromagnetic radiation and raise temperature around the tumour cells in the presence of an applied magnetic field, killing cancer cells through localised heating. In contrast to traditional strategies of crystal growth, orientated aggregation is a mediated approach in which primary crystallites assemble into secondary crystals. The mediator can be other particles, specific molecules or an applied field. NPs grown this way often exhibit different morphologies and properties to the starting material.

Images of multicore (a,b) and octahedral (d,e) NPs

The authors postulated that the use of an organic molecule that complexes with iron could be used to induce aggregation and chose p-tert-butylcalix[8]arene,  calixarene molecules are used in host-guest chemistry to induce efficient and selective hosts.  A reaction mixture of the calixarene, iron(III) acetylacetonate and oleic acid was heated at 200°C for 2 hours, before being refluxed for one hour to promote crystal growth. The initial ratio of the reactants (0.5:1:2) produced multicore NPs with an average size of 40nm and primary crystallites of 7nm. Raising the iron:calixarene ratio to 1:1 resulted in a new morphology being produced, octahedral NPs were now produced exclusively with an average size of 50nm. An experiment without the calixarene produced different NPs again, this time much smaller (7nm) single core NPs. Further experiments varying the heating time and ratios resulted in defect octahedral NPs.

The colloidal and magnetic properties of the NPs were then measured with the multicore structures exhibiting excellent properties. The authors conclude that their synthesis method is easy to perform, reproducible and controllable.

For more information, read the full paper at:

Tuning morphology and magnetism of magnetite nanoparticles by calix[8]arene-induced oriented aggregation

Francesco Vita,  Helena Gavilán, Francesca Rossi, César de Julián Fernández, Andrea Secchi, Arturo Arduini, Franca Albertini and  M. Puerto Morales

DOI: 10.1039/C6CE01252C

The 3rd China-India-Singapore (CIS) Symposium on Crystal Engineering was recently held at the Indian Institute of Science, Bangalore, India, 8–10 December, 2014.

The CIS symposium series on “Crystal Engineering” was conceived so that researchers from China, India and Singapore could meet, discuss, present and exchange their research work to accelerate the growth of crystal engineering.

The symposium series aims to discuss and acknowledge recent advances in the field of crystal engineering in the south Asian region. The 1st CIS Symposium on Crystal Engineering was held at National University of Singapore (NUS) from 30 July –
2 August, 2010. The 2nd CIS Symposium on Crystal Engineering was held at Guangzhou, China, 20–23 November, 2012.

The 3rd CIS Symposium on Crystal Engineering was recently organized by Professors Gautam. R. Desiraju and S. Natarajan at the Solid State and Structural Chemistry Unit, at the Indian Institute of Science. A total of 22 researchers from different institutes in China, India and Singapore presented their work, ranging from the research areas of porous materials and pharmaceutical solids to intermolecular interactions and computational chemistry. This symposium highlighted some of the recent developments in the field of organic, inorganic, pharmaceutical and organic-semiconductor materials achieved through the applications of crystal engineering.

The 3rd CIS Symposium on Crystal Engineering started with the welcome address from Prof. S. Natarajan (IISc, India) followed by inaugural speeches by Prof. Gautam R. Desiraju (IISc, India) and Prof. Shilun Qiu (Jilin University, China). This was followed by the first scientific lecture by Prof. X.M. Chen (Sun Yat-Sen University, China) on “Metal Organic Frameworks for Molecular Oxygen Sensing”. Prof. T.N. Guru Row (IISc Bangalore, India), Prof. A. Ramanan (IIT Delhi, India), and Prof. Cheng Peng (Nankai University, China) described the use of the crystal engineering concepts towards understanding the a) relevance of intermolecular interactions, b) structure and properties of metal carbarboxylate-based supramolecular assemblies and c) rational design of molecular magnetic materials. Other speakers of the first day were Prof. S. Aipitamula (A*STAR, Singapore), Prof. P. Dastidar (IACS, India), Prof. C. Malla Reddy (IISER Kolkata, India), Prof. P. Thilagar (IISc Bangalore, India), and Prof. P. Venugopalan (Punjab University, India).

On the second day of the meeting, Prof. J.J. Vittal (National University of Singapore, Singapore) outlined an interesting project on “Crystal Engineering of Photoreactive and Photosalient Crystals”. This was followed by the scientific lectures by Profs. Lu Tong-Bu (Sun Yet-Sen University, China), R. Banerjee (CSIR-NCL, India), V.R. Pedireddi (IIT Bhubaneswar, India), P.S. Mukherjee (IISc Bangalore, India), Su Cheng-Yong (Sun Yet-Sen University, China), J.N. Moorthy (IIT Kanpur, India), T.K. Maji (JNCASR, Bangalore, India), A. Nangia (University of Hyderabad, India), B. K. Saha (Pondicherry University, India) and Daliang Zhang (Jilin University, China).

Prof. Shilun Qiu, (Jilin University, China) delivered a stimulating talk on gas storage in metal-organic frameworks and covalent-organic frameworks during the final day of the meeting. His talk was followed by the scientific lectures by Profs. K. Biradha (IIT Kharagpur, India), and T.S Thakur (Central Drug Research Institute, India).

The next meeting will be held in 2016 as a South and East Asia Conference on Crystal Engineering, SEACCE. This meeting will aim to popularize the idea of crystal engineering in countries such as Bangladesh, Malaysia, Nepal, Pakistan, Sri Lanka, Thailand, and Vietnam. A resolution was signed by the participants from China, India and Singapore. The next meeting is likely to be held in Nepal, Sri Lanka or Bhutan in the summer of 2016.